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A321949
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Column k=4 of triangle A257673.
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3
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1, 12, 78, 376, 1509, 5340, 17234, 51796, 147054, 398388, 1037560, 2612520, 6387965, 15221412, 35446980, 80865304, 181076216, 398660292, 864186408, 1846759404, 3894731430, 8113669352, 16710519860, 34049851236, 68687627812, 137257430140, 271842916654
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OFFSET
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4,2
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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)^4. - Ilya Gutkovskiy, Jan 30 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))(4):
seq(a(n), n=4..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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