A137856 Row sums of triangle A137855.
1, 2, 4, 8, 17, 39, 97, 261, 756, 2343, 7722, 26917, 98789, 380360, 1531698, 6434385, 28130890, 127729730, 601196428, 2928369917, 14738842361, 76547694741, 409718539681, 2257459567236, 12789959138943, 74439150889080, 444647798089245, 2723583835351855
Offset: 1
Keywords
Examples
a(5) = 17 = sum of row 5 terms of triangle A137855: (1 + 2 + 5 + 8 + 1).
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..200
Programs
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PARI
a(n)={sum(k=1, n, sum(j=1, n-k+1, stirling(k,j,2)))} \\ Andrew Howroyd, Aug 09 2018
Formula
a(n) = Sum_{k=1..n} Sum_{j=1..n-k+1} Stirling2(k, j). - Andrew Howroyd, Aug 09 2018
Extensions
Terms a(12) and beyond from Andrew Howroyd, Aug 09 2018