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A015511
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a(1) = 1, a(n) = Sum_{k=1..n-1} ((9^k - 1)/8)*a(k).
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10
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1, 1, 11, 1012, 830852, 6133349464, 407444538242984, 243599680968409330048, 1310771150941736627904810368, 63477451180042308935531134194562816, 27666523379269090447091129488519658150671616
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OFFSET
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1,3
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LINKS
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FORMULA
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a(n) ~ QPochhammer(-63, 1/9) * 3^(n*(n-1)) / 2^(3*n+7). - Vaclav Kotesovec, May 03 2023
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MATHEMATICA
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a[n_, m_]:= a[n, m]= If[n<3, 1, (m^(n-1) +m-2)*a[n-1, m]/(m-1)];
Join[{1}, Table[7^n*QPochhammer[-1/7, 9, n]/2^(3*n + 1), {n, 2, 12}]] (* Vaclav Kotesovec, May 03 2023 *)
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PROG
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(Magma) [n le 2 select 1 else ((9^(n-1)+7)/8)*Self(n-1): n in [1..15]]; // Vincenzo Librandi, Nov 12 2012
(SageMath)
def a(n, m): return 1 if (n<3) else (m^(n-1)+m-2)*a(n-1, m)/(m-1)
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CROSSREFS
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Sequences with the recurrence a(n) = (m^(n-1) + m-2)*a(n-1)/(m-1): A036442 (m=2), A015502 (m=3), A015503 (m=4), A015506 (m=5), A015507 (m=6), A015508 (m=7), A015509 (m=8), this sequence (m=9), A015512 (m=10), A015513 (m=11), A015515 (m=12).
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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