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Search: id:A136559
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| A136559 |
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G.f.: A(x) = Sum_{n>=0} atanh( 2^(2n+1)*x )^(2n+1) / (2n+1)! ; a power series in x with integer coefficients. |
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+0
3
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| 2, 0, 88, 0, 285088, 0, 112173964160, 0, 6667221644498203136, 0, 66605167708510907980664608768, 0, 120169056821375322042225614651624227643392, 0
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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2^n divides a(n) for n>=0.
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EXAMPLE
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G.f.: A(x) = 2*x + 88*x^3 + 285088*x^5 + 112173964160*x^7 +...
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PROGRAM
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(PARI) {a(n)=polcoeff(sum(k=0, n\2, atanh(2^(2*k+1)*x +x*O(x^n))^(2*k+1)/(2*k+1)!), n)}
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CROSSREFS
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Cf. A136558.
Sequence in context: A012451 A012447 A136558 this_sequence A009740 A132860 A009270
Adjacent sequences: A136556 A136557 A136558 this_sequence A136560 A136561 A136562
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jan 10 2008
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