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A000320
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Generalized tangent numbers d(5,n).
(Formerly M3722 N1521)
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5
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4, 272, 55744, 23750912, 17328937984, 19313964388352, 30527905292468224, 64955605537174126592, 179013508069217017790464, 620314831396713435870789632, 2639743384489464189324523208704, 13533573366345611477262311433961472, 82274260343572247169162187576069586944
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
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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Lars Blomberg, Table of n, a(n) for n = 1..189
D. Shanks, Generalized Euler and class numbers. Math. Comp. 21 1967 663-688.
D. Shanks, Corrigenda to: "Generalized Euler and class numbers", Math. Comp. 22 (1968), 699
D. Shanks, Generalized Euler and class numbers, Math. Comp. 21 (1967), 689-694; 22 (1968), 699. [Annotated scanned copy]
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MATHEMATICA
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nmax = 15; km0 = 10; Clear[dd]; L[a_, s_, km_] := Sum[JacobiSymbol[-a, 2 k + 1]/(2k+1)^s, {k, 0, km}]; d[a_ /; a>1, n_, km_] := (2n-1)! L[-a, 2n, km] (2a/Pi)^(2n)/Sqrt[a] // Round; dd[km_] := dd[km] = Table[d[5, n, km], {n, 1, nmax}]; dd[km0]; dd[km = 2km0]; While[dd[km] != dd[km/2, km = 2 km]]; A000320 = dd[km] (* Jean-François Alcover, Feb 07 2016 *)
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CROSSREFS
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Cf. A000318.
Sequence in context: A119008 A108134 A221081 * A101758 A134786 A190635
Adjacent sequences: A000317 A000318 A000319 * A000321 A000322 A000323
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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Formula producing A000326, rather than this sequence, deleted by Sean A. Irvine, Sep 09 2010
a(10)-a(13) from Lars Blomberg, Sep 07 2015
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STATUS
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approved
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