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A270497
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Sum of the sizes of the fifth blocks in all set partitions of {1,2,...,n}.
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2
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1, 17, 184, 1641, 13276, 102244, 770989, 5795889, 43967302, 339403001, 2681449074, 21763977864, 181900742989, 1567473197429, 13932812925824, 127738400615689, 1207445992487256, 11759938209394472, 117926100082535985, 1216563820893322317, 12901060857158377838
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OFFSET
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5,2
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LINKS
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MAPLE
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b:= proc(n, m) option remember; `if`(n=0, [1, 0],
add((p->`if`(j<6, [p[1], p[2]+p[1]*x^j], p))(
b(n-1, max(m, j))), j=1..m+1))
end:
a:= n-> coeff(b(n, 0)[2], x, 5):
seq(a(n), n=5..30);
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MATHEMATICA
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b[n_, m_] := b[n, m] = If[n == 0, {1, 0}, Sum[Function[p, If[j < 6, {p[[1]], p[[2]] + p[[1]]*x^j}, p]][b[n - 1, Max[m, j]]], {j, 1, m + 1}]];
a[n_] := Coefficient[b[n, 0][[2]], x, 5];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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