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%I
%S 0,1,5,13,41,121,365,1093,3281,9841,29525,88573,265721,797161,2391485,
%T 7174453,21523361,64570081,193710245,581130733,1743392201,5230176601,
%U 15690529805,47071589413,141214768241,423644304721,1270932914165
%N Binomial transform of Jacobsthal gap sequence (A080924).
%F a(n)=Sum{k=1..n, Binomial(n, 2k-2)2^(2k-2)}
%F 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_, May 19 2003
%Y Cf. A046717, A080926.
%K easy,nonn
%O 0,3
%A _Paul Barry_, Feb 26 2003
%E Removed duplicate of a formula - _R. J. Mathar_, Sep 03 2009
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