**a(0) = 0; for n>0, a(n) = Sum_k={0..n-1} Bell(k), where the Bell numbers Bell(k) are given in A000110.**

*0, 1, 2, 4, 9, 24, 76, 279, 1156, 5296, 26443, 142418, 820988, 5034585, 32679022*

*1 seqfan posts*

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

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