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A009329
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E.g.f. log(1+sin(tan(x))).
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3
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0, 1, -1, 3, -10, 41, -232, 1299, -10064, 74609, -720384, 6787811, -78009600, 898506649, -11977120768, 163241051315, -2480763381760, 39007280136801, -666957211828224, 11866656488375747, -225809770695098368
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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(n) = 4*sum(k=0..(n-1)/2, ((-1)^(n-k+1)*sum(r=0..k, ((sum(i=0..(n-2*k)/2, (2*i-n+2*k)^(2*r+n-2*k)*(-1)^i*binomial(n-2*k,i)))*sum(j=2*r+n-2*k..n, binomial(j-1,2*r+n-2*k-1)*j!*2^(n-j-1)*(-1)^(j)*stirling2(n,j)))/(2*r+n-2*k)!))/((n-2*k)*2^(n-2*k))). - Vladimir Kruchinin, Jun 11 2011
a(n) ~ 2 * (-1)^(n+1) * (n-1)! / arctan(Pi/2)^n. - Vaclav Kotesovec, Jun 26 2014
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MATHEMATICA
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CoefficientList[Series[Log[1+Sin[Tan[x]]], {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Jun 26 2014 *)
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PROG
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(Maxima)
a(n):=4*sum(((-1)^(n-k+1)*sum(((sum((2*i-n+2*k)^(2*r+n-2*k)*(-1)^i*binomial(n-2*k, i), i, 0, (n-2*k)/2))*sum(binomial(j-1, 2*r+n-2*k-1)*j!*2^(n-j-1)*(-1)^(j)*stirling2(n, j), j, 2*r+n-2*k, n))/(2*r+n-2*k)!, r, 0, k))/((n-2*k)*2^(n-2*k)), k, 0, (n-1)/2); /* Vladimir Kruchinin, Jun 11 2011*/
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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