OFFSET
1,1
COMMENTS
See A067567 for a conjecture about this sequence from Peter Bala.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
EXAMPLE
G.f. = 2*x + 17*x^2 + 66*x^3 + 218*x^4 + 564*x^5 + 1407*x^6 + 3074*x^7 + ...
MATHEMATICA
a[n_]:= (2/n)*Sum[k^3*PartitionsP[k]*PartitionsP[n-k], {k, 1, n}]; Table[a[n], {n, 1, 50}] (* G. C. Greubel, Jul 29 2018 *)
PROG
(PARI) {a(n) = if( n<1, 0, sum(k=1, n, k^3 * numbpart(k) * numbpart(n-k)) * 2 / n)};
CROSSREFS
KEYWORD
nonn
AUTHOR
Michael Somos, Jan 28 2017
STATUS
approved