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A009118
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E.g.f. cos(x/cos(x)) (even powers only).
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1
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1, -1, -11, -181, -3863, -66121, 4478365, 1211701763, 226423491793, 43068302925551, 8876725117679941, 1997577117130009403, 483811389670392875449, 121594250947356501211559, 28960468994349845642813677
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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FORMULA
| a(n)=2*sum(m=1..n-1, binomial(2*n,2*m)*sum(j=0..n-m, binomial(m+j-1,j)*4^(n-m-j)*sum(i=0..j, (i-j)^(2*n-2*m)*binomial(2*j,i)*(-1)^(n+j-i))))+(-1)^n; [From Vladimir Kruchinin, Jun 28 2011]
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PROG
| (Maxima)
a(n):=2*sum(binomial(2*n, 2*m)*sum(binomial(m+j-1, j)*4^(n-m-j)*sum((i-j)^(2*n-2*m)*binomial(2*j, i)*(-1)^(n+j-i), i, 0, j), j, 0, n-m), m, 1, n-1)+(-1)^n; [From Vladimir Kruchinin, Jun 28 2011]
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CROSSREFS
| Sequence in context: A036935 A205088 A143413 * A112943 A057618 A068648
Adjacent sequences: A009115 A009116 A009117 * A009119 A009120 A009121
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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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