The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A225549 a(n) is the number of terms in the expansion of (x-y)*(x^4-y^4)*(x^9-y^9)*...*(x^(n^2)-y^(n^2)). 2
 2, 4, 8, 16, 24, 40, 68, 103, 162, 236, 344, 453, 612, 790, 994, 1229, 1432, 1782, 2134, 2517, 2968, 3460, 3974, 4543, 5160, 5822, 6546, 7347, 8184, 9080, 10058, 11075, 12166, 13316, 14536, 15837, 17202, 18654, 20156, 21765, 23450, 25212, 27074, 29001, 31032, 33158, 35370, 37679, 40070, 42578 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS In the definition one can take y=1. Thus the sequence becomes the number of terms in the polynomial of the product{k=1..n} (1-x^(k^2)). LINKS Table of n, a(n) for n=1..50. MATHEMATICA a[n_] := Length@ ExpandAll@ Product[(1 - x^(k^2)), {k, n}]; Array[f, 40] PROG (PARI) a(n)=my(P=prod(k=1, n, 1-'x^k^2)); sum(i=0, poldegree(P), polcoeff(P, i)!=0) \\ Charles R Greathouse IV, May 10 2013 CROSSREFS Cf. A000124, A086781, A086795, A086796, A086817. Sequence in context: A224815 A031923 A304076 * A138278 A326078 A089827 Adjacent sequences: A225546 A225547 A225548 * A225550 A225551 A225552 KEYWORD nonn AUTHOR Yuval Dekel (dekelyuval(AT)hotmail.com) and Robert G. Wilson v, May 10 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 24 22:09 EDT 2024. Contains 372782 sequences. (Running on oeis4.)