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A256168
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Coefficients in asymptotic expansion of sequence A052186.
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10
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1, -2, 1, -1, -9, -59, -474, -4560, -50364, -625385, -8622658, -130751886, -2163331779, -38793751015, -749691306018, -15535914341831, -343749787006758, -8089725377931547, -201801866906374263, -5319643146604299835, -147774950436327236681
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OFFSET
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0,2
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COMMENTS
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For k > 2 is a(k) negative.
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LINKS
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FORMULA
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a(k) ~ -(k-1)! / (log(2))^k.
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EXAMPLE
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A052186(n) / n! ~ 1 - 2/n + 1/n^2 - 1/n^3 - 9/n^4 - 59/n^5 - 474/n^6 - ...
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MATHEMATICA
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nmax = 30; b = CoefficientList[Assuming[Element[x, Reals], Series[E^(2/x) / (ExpIntegralEi[1/x] + E^(1/x))^2, {x, 0, nmax}]], x]; Flatten[{1, Table[Sum[b[[k+1]]*StirlingS2[n-1, k-1], {k, 1, n}], {n, 1, nmax}]}] (* Vaclav Kotesovec, Aug 03 2015 *)
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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