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A352839
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Expansion of g.f. 1/(1 - Sum_{k>=1} sigma_k(k) * x^k).
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1
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1, 1, 6, 39, 370, 4132, 59288, 990705, 19577018, 439550259, 11142216938, 313147651821, 9680830606850, 325944181383936, 11875777329091878, 465292113335910106, 19507503314546762246, 871248546067010133794, 41295079536653463057146
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OFFSET
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0,3
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LINKS
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FORMULA
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a(0) = 1; a(n) = Sum_{k=1..n} sigma_k(k) * a(n-k).
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PROG
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(PARI) my(N=20, x='x+O('x^N)); Vec(1/(1-sum(k=1, N, sigma(k, k)*x^k)))
(PARI) a(n) = if(n==0, 1, sum(k=1, n, sigma(k, k)*a(n-k)));
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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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