A117263 Row sums of triangle A117262; also, self-convolution of A117264.

1, 2, 7, 64, 1729, 140050, 34032151, 24809438080, 54258241080961, 355988319732185122, 7006918097288599756327, 413751506726794527011353024, 73294838162131470076480154142529

Offset

0,2

Links

Table of n, a(n) for n=0..12.

Formula

a(n) = Sum_{k=0..n} 3^( n*(n-1)/2 - k*(k-1)/2 ).

G.f. A(x) satisfies: A(x) = 1/(1 - x) + x * A(3*x). - Ilya Gutkovskiy, Jun 06 2020

Prog

(PARI) a(n)=sum(k=0, n, 3^((n-k)*(n+k-1)/2))

Crossrefs

Cf. A117261, A117262, A117264.

Sequence in context: A346781 A011821 A366705 * A046855 A179043 A116985

Adjacent sequences: A117260 A117261 A117262 * A117264 A117265 A117266

Keyword

nonn

Author

Paul D. Hanna, Mar 14 2006

Status

approved