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URL: https://oeis.org/A352839

⇱ A352839 - OEIS

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A352839
Expansion of g.f. 1/(1 - Sum_{k>=1} sigma_k(k) * x^k).
1
1, 1, 6, 39, 370, 4132, 59288, 990705, 19577018, 439550259, 11142216938, 313147651821, 9680830606850, 325944181383936, 11875777329091878, 465292113335910106, 19507503314546762246, 871248546067010133794, 41295079536653463057146
OFFSET
0,3
FORMULA
a(0) = 1; a(n) = Sum_{k=1..n} sigma_k(k) * a(n-k).
PROG
(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)));
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 05 2022
STATUS
approved