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A321384
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a(1) = 1; a(n+1) = -Sum_{d|n} d*a(d).
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2
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1, -1, 1, -4, 17, -86, 514, -3599, 28809, -259285, 2592766, -28520427, 342245654, -4449193503, 62288705445, -934330581764, 14949289337033, -254137918729562, 4574482536873349, -86915168200593632, 1738303364014465422, -36504370644303777464, 803096154174654583783, -18471211546017055427010
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OFFSET
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1,4
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LINKS
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FORMULA
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L.g.f.: log(Product_{n>=1} (1 - x^n)^a(n)) = Sum_{n>=1} a(n+1)*x^n/n.
a(n) ~ -(-1)^n * c * (n-1)!, where c = 0.7144978951771230847588633755835851845867260778566988217176856019246992... - Vaclav Kotesovec, Nov 09 2018
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MATHEMATICA
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a[1] = 1; a[n_] := a[n] = -Sum[d a[d], {d, Divisors[n - 1]}]; Table[a[n], {n, 24}]
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PROG
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(PARI) a(n) = if (n==1, 1, -sumdiv(n-1, d, d*a(d))); \\ Michel Marcus, Nov 09 2018
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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