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A006523
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Sum ((-1)^(i+1)*binomial(n,i)*2^i*(2*n-1)!,i=1..n) for n odd.
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0
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2, 240, 725760, 12454041600, 711374856192000, 102181884343418880000, 31022420086661971968000000, 17683523987479403909087232000000, 17366635237623772991036388802560000000, 27527506182452690092631959163161804800000000
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OFFSET
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1,1
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LINKS
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FORMULA
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PROG
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(PARI) a(n) = n=2*n-1; sum(i=1, n, (-1)^(i+1)*binomial(n, i)*2^i*(2*n-1)!); \\ Michel Marcus, Oct 08 2023
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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