OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..468
EXAMPLE
a(0) = 1;
a(1) = 1*C(0,0) + 1*C(0,1) = 1;
a(2) = 1*C(0,0) + 2*C(1,1) + 1*C(0,2) = 1 + 2*1 + 0 = 3;
a(3) = 1*C(0,0) + 3*C(2,1) + 3*C(2,2) + 1*C(0,3) = 1 + 3*2 + 3*1 + 0 = 10;
a(4) = 1*C(0,0) + 4*C(3,1) + 6*C(4,2) + 4*C(3,3) + 1*C(0,4) = 1 + 4*3 + 6*6 + 4 + 0 = 53; ...
MATHEMATICA
Table[Sum[Binomial[n, k] * Binomial[(n-k)*k, k], {k, 0, n}], {n, 0, 20}] (* Vaclav Kotesovec, Aug 22 2017 *)
PROG
(PARI) {a(n) = sum(k=0, n, binomial(n, k)*binomial((n-k)*k, k))}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 18 2015
STATUS
approved