OEIS @ 

Look up a number sequence in the On-Line Encyclopedia of Integer Sequences
by typing  consecutive  numbers from your sequence of interest (signs are optional):

SeqFan Mailing List:  For integer sequences enthusiasts (French or English).

OEIS 100K E-Party:  Join N.J.A. Sloane in celebrating over 100 000 sequences
in this  wonderful  collection, 40 years in the making...  Here are my contributions:

• A162512 (2009-07-05)  Multiplicative function:  a(p^e) = -(-2)^(e-1)
• A162511 (2009-07-05)  Multiplicative function:  a(p^e) = (-1)^(e-1).
• A162510 (2009-07-05)  Multiplicative function:  a(p^e) = 2^(e-1).
• A160679 (2009-06-25)  Square-roots of nimbers.
• A160678 (2009-06-06)  Numbers  n  whose abundancy  s(n)/n  is  13/2.
• A160115 (2009-05-06)  Fluctuations in the number of cubefree integers (binary).
• A160114 (2009-05-06)  Fluctuations in the number of cubefree integers (decimal).
• A160113 (2009-05-02)  Number of cubefree integers with n bits.
• A160112 (2009-05-02)  Number of cubefree integers with n digits.
• A143314 (2008-08-06)  Poker hands of n cards containing a straight flush.
• A141385 (2008-07-02)  A sequence obeying a third-order linear recurrence.
• A141384 (2008-06-28)  Traces of the powers of an order-8 adjacency matrix.
• A140076 (2008-06-01)  Pierce expansion of the cube root of 1/2.
• A140074 (2008-05-06)  Excess count of the perfect squares between cubes.
• A129667 (2007-04-28)  Dirichlet inverse of  the Abelian group count.
• A120630 (2006-06-24)  Dirichlet inverse of  ¼ card( {(x,y) | x²+y² = n} )
• A120629 (2006-06-20)  Nonpowers < 0, with squarefree part ¹ 1 mod 4.
• A108942 (2005-07-20)  Obsolete.  See note below.
• A101188 (2004-12-08)  (7m+1)(8m+1)(11m+1) is a Carmichael number.
• A101187 (2004-12-03)  (6k+1)(12k+1)(18k+1) is a Carmichael number.
• A101186 (2004-12-03)  m=1848+942k makes 7m+1,8m+1,11m+1 prime.
• A101088 (2004-11-30)  Prime values of   | B101086(k) |.
• A101087 (2004-11-30)  Values of k for which  | B101086(k) |  is prime.
• B101086 (2004-11-30)  a(0) = 0;   a(1) = 1;   a(n+2)  =  a(n+1) - 2 a(n).
• A101035 (2004-11-27)  Dirichlet inverse of the gcd-sum function.
• A058789 (2000-11-30)  n-hedra with n+1 vertices (and/or 2n-1 edges).
• A058788 (2000-11-29)  Table:  Polyhedra with n edges and k nodes.
• A058787 (2000-11-29)  Table:  Polyhedra with n faces and k vertices.
• A058786 (2000-11-29)  n-hedra with 2n-5 vertices (and/or 3n-7 edges).
   
  In addition, I had a few comments to make on sequences contributed by others:
• A048943 (2010-10-10)  Characterizing integers whose divisor product is square.
• A162530 (2009-07-12)  A few more terms in an easy sequence.
• A159271 (2009-07-01)  Numbers of abundancy 11/2.  Table & factorizations.
• A088912 (2009-06-10)  Guy Robin's theorem (1984) & Riemann's hypothesis.
• A055153 (2009-06-04)  88898072401645056  has abundancy  7/2.
• A077006 (2009-05-20)  360360 ties the record abundancy (48/11) of 332640.
• A055153 (2009-05-10)  22290964134962716779872256  has abundancy  7/2.
• A141645 (2009-05-10)  200286975596707184640  has abundancy  9/2.
• A004709 (2009-05-06)  Cubefree integers.
• A071172 & A053462 (2009-04-30)  Squarefree integers with fewer than n digits.
• A143658 (2009-04-30)  Number of squarefree integers with n+1 bits or less.
• A048954 (2009-01-16)  Factorization of  Wn  (up to n=114, as of 2007-11-11).
• A003277 (2008-01-08)  These  are all the divisors of Carmichael numbers...

Notes :

A108942  (which is now an unrelated sequence)  was created on 2005-07-20 by Jonathan Vos Post (whom I befriended electronically only  much  later)  as a home for the  finite  sequence  (0,1,2,3,4,5,6,7,9,18,33).  Jonathan posted that with a reference to an article of mine and a piece of prose cut-and-pasted from it  (his motivations are explained elsewhere).  On 2009-10-24, M. F. Hasler  pointed out that the thing had already been filed much earlier as A007496, which is where the aforementioned prose can now be found.  This goes to show that almost every "cute" sequence is likely to be  already  part of OEIS.  Read before you write!

The simple sequence listed above as B101086 is not part of OEIS, although it was submitted at the indicated date, because it differs from two previously listed sequences  (A001607 and A077020)  by  signs  only.  Yet, that sequence has the simplest closed form among its siblings.  Originally, the EIS  (not yet "Online")  was essentially devised as a collection of unsigned sequences  (in the early printed versions, the lexicographic organization of the integer sequences was insensitive to signs).  This  historical bias  is still present in the current OEIS.  For example, I submitted A120629 as a sequence consisting entirely of  negative  values  (arguably, that's the best way ro present it).  It was immediately retitled and recorded as a sequence of absolute values, which now stands...

	Gérard P. Michon, Ph.D.

Neologisms: Here are the neologisms I coined  (I don't know where else to put that list). I would have been glad to adopt pre-existing terminology but I couldn't find any. 1983: : Inert games  (suggested by Judea Pearl). 2000:  Hemiprism.  Hemicube. 2000:  Antiwedge.  In particular:  tetragonal antiwedge.  See Wikipedia: Hexahedron   (before 2007-09-17). 2001:  Scalene ellipsoid  (an ellipsoid which need not be a spheroid). 2002:  Thermal wring.  The  pressure   W = r Cp / Tb2 2004:  Thomsen's formula. 2007:  Cliff:  Open line of discontinuity in a function of a complex variable. 2008:  Gauss-Weber Law  or  Pélerin's Law  (1269). 2008:  Mosengeil's Formula  (1906).  T = To / g 2009:  Hemiperfect numbers  (with abundancies 3/2, 5/2, 7/2, 9/2...). 2009:  Multiplicative parity:   g(n) = (-1)w(n) 2011:  Tannery's hourglass (double pear):   8 a2 (x2 + y2 )  =  (a2 - z2 ) z2		Hemicube
The above list is mostly for my own records, but it might help others trace the origins of words.

Search    for:

---