**a(0) = 1, a(1) = 3; for n>1, a(n) = 2*a(n-1) + 4*a(n-2).**

*1, 3, 10, 32, 104, 336, 1088, 3520, 11392, 36864, 119296, 386048, 1249280*

*3 seqfan posts*

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

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