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A005801
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Generalized tangent numbers of type 3^(2n+1).
(Formerly M5218)
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0
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0, 30, 217800, 16294301520, 6544151202877440, 9764950519194817858560, 42762698240957239228617722880, 466476501707480855594001261422438400, 11235366943887873286558941529247982529413120
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OFFSET
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0,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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a(n) = 1/3^(2*n+1) * Sum_{i=0..2*n+1} (-1)^(i+1) * 2^-i * binomial(2*n+1, i) * A000182(n+i+1).
a(n) ~ 2^(1/2)*3^(-1/2)*Pi^(-1/2)*n^(-1/2)*2^(8*n)*3^(-3*n)*{1 - 13/144*n^-1 + 169/41472*n^-2 + 48635/17915904*n^-3 - ...}. - Joe Keane (jgk(AT)jgk.org), Nov 07 2003
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MATHEMATICA
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a000182[n_] := (4^n*(4^n-1)*Abs[BernoulliB[2*n]])/(2*n); a[n_] := Sum[((-1)^(i+1)*Binomial[2*n+1, i]*a000182[n+i+1])/2^i, {i, 0, 2*n+1}]/3^(2*n+1)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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More terms from Joe Keane (jgk(AT)jgk.org), Nov 07 2003
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STATUS
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approved
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