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A013369
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Expansion of e.g.f. exp(sin(x)-sinh(x)).
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3
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1, 0, 0, -2, 0, 0, 40, -2, 0, -2240, 480, -2, 246400, -137280, 8320, -44844802, 51251200, -10325120, 12197916160, -24831206402, 11394406400, -4636033573760, 15296025241600, -13230894476802, 2348235343872000
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OFFSET
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0,4
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LINKS
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FORMULA
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a(0) = 1; a(n) = -2 * Sum_{k=0..floor((n-3)/4)} binomial(n-1,4*k+2) * a(n-4*k-3). - Seiichi Manyama, Mar 17 2022
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EXAMPLE
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1-2/3!*x^3+40/6!*x^6-2/7!*x^7-2240/9!*x^9...
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MATHEMATICA
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With[{nn=30}, CoefficientList[Series[Exp[Sin[x]-Sinh[x]], {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, May 13 2020 *)
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PROG
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(PARI) my(N=40, x='x+O('x^N)); Vec(serlaplace(exp(sin(x)-sinh(x)))) \\ Seiichi Manyama, Mar 17 2022
(PARI) a(n) = if(n==0, 1, -2*sum(k=0, (n-3)\4, binomial(n-1, 4*k+2)*a(n-4*k-3))); \\ Seiichi Manyama, Mar 17 2022
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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Patrick Demichel (patrick.demichel(AT)hp.com)
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EXTENSIONS
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STATUS
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approved
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