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Search: id:A067621
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| A067621 |
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Let t = coefficient of x^(2n+1) in expansion of sin(x)/(1-x^2); a(n)=denominator(t)-numerator(t). |
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+0
1
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| 0, 1, 19, 799, 57527, 6327971, 39486539, 207304329751, 4337444437867, 19284277970756683, 8099396747717806859, 819658950869042054131, 2458976852607126162392999, 1726201750530202565999885299
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Old description: consider the power series of sin(x)/(x+1)=N(0)/D(0)*(x-x^2)+...+N(k)/D(k)*(x^(2k+1)-x^(2k+2))+...; then a(n)=D(n)-N(n).
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FORMULA
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a(n) is the difference between denominator and numerator of sum(i=0, n, (-1)^i/(2i+1)!)
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PROGRAM
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(PARI) a(n)=local(t); if(n<0, 0, t=polcoeff(sin(x+O(x^(2*n+2)))/(1-x^2), 2*n+1); denominator(t)-numerator(t)) - Michael Somos Feb 01 2004
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CROSSREFS
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Sequence in context: A041687 A041684 A157165 this_sequence A135562 A139194 A005535
Adjacent sequences: A067618 A067619 A067620 this_sequence A067622 A067623 A067624
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Feb 02 2002
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