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A080925 Binomial transform of Jacobsthal gap sequence (A080924). 5
0, 1, 5, 13, 41, 121, 365, 1093, 3281, 9841, 29525, 88573, 265721, 797161, 2391485, 7174453, 21523361, 64570081, 193710245, 581130733, 1743392201, 5230176601, 15690529805, 47071589413, 141214768241, 423644304721, 1270932914165 (list; graph; refs; listen; history; internal format)
OFFSET

0,3

FORMULA

a(n)=Sum{k=1..n, Binomial(n, 2k-2)2^(2k-2)}

a(n)=(3^n-2*0^n+(-1)^n)/2; G.f.: x(1+3x)/((1+x)(1-3x)); E.g.f.: (exp(3x)-2exp(0)+exp(-x))/2. - Paul Barry (pbarry(AT)wit.ie), May 19 2003

CROSSREFS

Cf. A046717, A080926.

Sequence in context: A200150 A046717 * A164907 A085601 A147718 A111009

Adjacent sequences:  A080922 A080923 A080924 * A080926 A080927 A080928

KEYWORD

easy,nonn

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Feb 26 2003

EXTENSIONS

Removed duplicate of a formula - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 03 2009

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Last modified February 16 02:30 EST 2012. Contains 205860 sequences.