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A321954
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Column k=9 of triangle A257673.
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3
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1, 27, 378, 3681, 28134, 180198, 1007370, 5051790, 23173047, 98644395, 394006761, 1489460724, 5365964511, 18526724685, 61587671283, 197885754837, 616568620176, 1868127089697, 5517376711191, 15917134652829, 44935916034951, 124340811582540, 337706753653476
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listen;
history;
text;
internal format)
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OFFSET
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9,2
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LINKS
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FORMULA
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G.f.: (-1 + Product_{k>=1} 1 / (1 - x^k)^k)^9. - Ilya Gutkovskiy, Jan 31 2021
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MAPLE
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b:= proc(n, k) option remember; `if`(n=0, 1, k*add(
b(n-j, k)*numtheory[sigma][2](j), j=1..n)/n)
end:
a:= n-> (k-> add(b(n, k-i)*(-1)^i*binomial(k, i), i=0..k))(9):
seq(a(n), n=9..35);
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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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