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

0,2

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

Cf. variants: A006896, A135756.

Sequence in context: A238818 A199574 A320489 * A337699 A370615 A051185

Adjacent sequences: A135752 A135753 A135754 * A135756 A135757 A135758

Keyword

nonn

Author

Paul D. Hanna, Nov 27 2007

Status

approved