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A009015
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E.g.f. cos(x*cos(x)) (even powers only).
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0
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1, -1, 13, -181, 3865, -140521, 6324517, -344747677, 23853473329, -1996865965009, 193406280000061, -21615227339380357, 2778071540350106953, -403985610499148666041, 65635628800688339178325
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(n)=sum(j=0..(2*n-1)/2, binomial(2*n,2*j)*((sum(i=0..((2*j-1)/2),(j-i)^(2*n-2*j)*binomial(2*j,i)))*(-1)^(n))/(2^(4*j-2*n-1)))+(-1)^n; [From Vladimir Kruchinin, Jun 06 2011]
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MATHEMATICA
| Cos[ Cos[ x ]*x ] (* Even Part *)
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PROG
| (Maxima)
a(n):=sum(binomial(2*n, 2*j)*((sum((j-i)^(2*n-2*j)*binomial(2*j, i), i, 0, ((2*j-1)/2)))*(-1)^(n))/(2^(4*j-2*n-1)), j, 0, (2*n-1)/2)+(-1)^n; [From Vladimir Kruchinin, Jun 06 2011]
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CROSSREFS
| Sequence in context: A122571 A001570 A020544 * A067385 A097260 A178303
Adjacent sequences: A009012 A009013 A009014 * A009016 A009017 A009018
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KEYWORD
| sign
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AUTHOR
| R. H. Hardin (rhhardin(AT)att.net)
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EXTENSIONS
| Extended with signs Mar 15 1997 by Olivier Gerard.
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