OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..49
FORMULA
a(n) ~ 3^(n*(n-1)/2). - Vaclav Kotesovec, Nov 27 2017
MATHEMATICA
Table[Sum[Binomial[n, k]*3^(Binomial[k, 2]), {k, 0, n}], {n, 0, 10}] (* G. C. Greubel, Nov 07 2016 *)
PROG
(PARI) {a(n)=sum(k=0, n, binomial(n, k)*3^(k*(k-1)/2))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Nov 27 2007
STATUS
approved