A135755 a(n) = Sum_{k=0..n} C(n,k)*3^[k*(k-1)/2].

1, 2, 6, 40, 860, 63000, 14714728, 10562062112, 22960880409360, 150300904214651680, 2955814683617734854752, 174481716707875308905153664, 30905247968182392588500030233024

Offset: 0

Author

Paul D. Hanna, Nov 27 2007

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..49

Crossrefs

Cf. variants: A006896, A135756.

Programs

Mathematica

Table[Sum[Binomial[n, k]*3^(Binomial[k, 2]), {k,0,n}], {n,0,10}] (* G. C. Greubel, Nov 07 2016 *)

PARI

{a(n)=sum(k=0,n,binomial(n,k)*3^(k*(k-1)/2))}

Formula

a(n) ~ 3^(n*(n-1)/2). - Vaclav Kotesovec, Nov 27 2017