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Search: id:A087208
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| A087208 |
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Expansion of exp(x)/(1-x^2). |
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+0
3
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| 1, 1, 3, 7, 37, 141, 1111, 5923, 62217, 426457, 5599531, 46910271, 739138093, 7318002277, 134523132927, 1536780478171, 32285551902481, 418004290062513, 9879378882159187, 142957467201379447, 3754163975220491061
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OFFSET
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0,3
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FORMULA
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a(n) = Sum_{k=0..floor(n/2)} n!/(n-2*k)!.
a(n) = n*(n-1)*a(n-2) + 1. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 24 2004
a(n) = (A000522(n)+(-1)^n*A000166(n))/2. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Aug 24 2004
a(n)=sum{k=0..n, binomial(n, k)(1+(-1)^k)k!/2} Binomial transform of A010050 (with interpolated zeros). - Paul Barry (pbarry(AT)wit.ie), Sep 14 2004
a(n) = Sum[P(n, k)[1, 0, 1, 0, 1, 0...](k), {k, 0, n}]. - Ross La Haye (rlahaye(AT)new.rr.com), Aug 29 2005
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CROSSREFS
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Cf. A002747.
Sequence in context: A049493 A020463 A057625 this_sequence A086031 A042895 A061931
Adjacent sequences: A087205 A087206 A087207 this_sequence A087209 A087210 A087211
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KEYWORD
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nonn
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AUTHOR
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Vladeta Jovovic (vladeta(AT)Eunet.yu), Oct 19 2003
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