**G.f.: (1+x^2)/((1-3x)(1-x-x^2)); a(n)=4a(n-1)-2a(n-2)-3a(n-3); a(n)=2*3^n-Fib(n+2); a(n)=sum{k=0..n, (L(k)-0^k)3^(n-k)}.**

*1, 4, 15, 49, 154, 473, 1437, 4340, 13067, 39277, 117954, 354061, 1062505*

*1 seqfan posts*

Index of A-numbers in seqfan: by ascending order by month by frequency by keyword

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