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Search: id:A053987
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| A053987 |
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Numerators of successive convergents to tan(1/2) using continued fraction 1/(2-1/(6-1/(10-1/(14-1/(18-1/(22-1/(26-1/30-...))))))). |
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+0
2
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| 1, 6, 59, 820, 14701, 322602, 8372951, 250865928, 8521068601, 323549740910, 13580568049619, 624382580541564, 31205548459028581, 1684475234207001810, 97668358035547076399
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)=sum(k=0, floor((n-1)/2), (-1)^k*(2*n-2*k-1)!/(n-2*k-1)!/(2*k+1)!) - Benoit Cloitre (benoit7848c(AT)orange.fr), Jan 03 2006
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PROGRAM
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(PARI) a(n)=sum(k=0, floor((n-1)/2), (-1)^k*(2*n-2*k-1)!/(n-2*k-1)!/(2*k+1)!) (Cloitre)
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CROSSREFS
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Cf. A053988.
Adjacent sequences: A053984 A053985 A053986 this_sequence A053988 A053989 A053990
Sequence in context: A089153 A075136 A024382 this_sequence A024270 A024271 A098185
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KEYWORD
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easy,frac,nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 03 2000
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