A156296 a(1)=1, a(n) = 2 * Sum_{k=1..n-1} (3^k-1)/2 * a(k) for n>=2.

1, 2, 10, 140, 5740, 700280, 255602200, 279628806800, 917462115110800, 9029662136920493600, 266600774592577573540000, 23613897008762965998731960000, 6274708327065504088149055143160000

Offset

0,2

Links

Michael De Vlieger, Table of n, a(n) for n = 0..64

Formula

a(n) = 2*A015502(n+1) for n>1. - Joe Slater, Mar 23 2017

Mathematica

Table[QPochhammer[-1, 3, n+1]/2^(n+1), {n, 0, 15}] (* Vaclav Kotesovec, Mar 24 2017 *)

Crossrefs

Sequence in context: A091990 A014228 A059475 * A003046 A337072 A294115

Adjacent sequences: A156293 A156294 A156295 * A156297 A156298 A156299

Keyword

nonn,easy

Author

Roger L. Bagula, Feb 07 2009

Extensions

New name from Joerg Arndt, Mar 24 2017

Status

approved