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A156296 a(1)=1, a(n) = 2 * Sum_{k=1..n-1} (3^k-1)/2 * a(k) for n>=2. 2
1, 2, 10, 140, 5740, 700280, 255602200, 279628806800, 917462115110800, 9029662136920493600, 266600774592577573540000, 23613897008762965998731960000, 6274708327065504088149055143160000 (list; graph; refs; listen; history; text; internal format)
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 A294115 A137884

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

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Last modified February 25 08:46 EST 2018. Contains 299647 sequences. (Running on oeis4.)