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A009081
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E.g.f. is cos(tan(x)/cos(x)), coefficients of even powers of x.
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1
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1, -1, -19, -517, -18023, -587529, 19183749, 12219870323, 3379214470193, 883981857320943, 238930492488456221, 66829754023676225259, 18410558239851140719561, 4167711609283156286652647, -82954815883633697917244747, -1284116651310135986426544039581
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OFFSET
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0,3
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COMMENTS
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All coefficients of odd powers of x are zero.
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LINKS
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MATHEMATICA
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With[{nn=30}, Take[CoefficientList[Series[Cos[Tan[x]/Cos[x]], {x, 0, nn}], x]Range[0, nn]!, {1, -1, 2}]] (* Harvey P. Dale, Jan 28 2012 *)
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PROG
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(PARI)
x='x+O('x^66); /* that many terms */
v=Vec(serlaplace(cos(tan(x)/cos(x))));
vector(#v\2, j, v[2*j-1]) /* show terms */
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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