**a(0) = 1; a(n+1) = Sum_{k, 0<=k<=n} a(k)*A001147(n-k), where A001147 = double factorial numbers.**

*1, 1, 2, 6, 26, 158, 1282, 13158, 163354, 2374078, 39456386, 737125446*

*1 seqfan posts*

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

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