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A015507
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a(1) = 1, a(n) = Sum_{k=1..n-1} ((6^k - 1)/5)*a(k).
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10
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1, 1, 8, 352, 91520, 142405120, 1328924579840, 74403829376081920, 24994031979330942894080, 50376471215620688640734003200, 609214555257707874214915513922355200, 44204249911340791820804231319883906967142400
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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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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)];
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PROG
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(Magma) [n le 2 select 1 else ((6^(n-1)+4)/5)*Self(n-1): n in [1..15]]; // Vincenzo Librandi, Nov 12 2012
(SageMath)
@CachedFunction
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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), this sequence (m=6), A015508 (m=7), A015509 (m=8), A015511 (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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