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A261253
Coefficients in an asymptotic expansion of sequence A261239.
7
1, -4, 2, -2, -31, -288, -2939, -33944, -438614, -6266312, -98050303, -1667563622, -30631857759, -604518210964, -12758658946466, -286833669370926, -6844757550430019, -172833310268551740, -4604828067485736507, -129123684195177403168, -3801830662346341617586
OFFSET
0,2
LINKS
FORMULA
a(k) ~ -k! / (log(2))^(k+1).
For n>0, a(n) = Sum_{k=1..n} A261254(k) * Stirling2(n-1, k-1).
EXAMPLE
A261239(n)/(-3*n!) ~ 1 - 4/n + 2/n^2 - 2/n^3 - 31/n^4 - 288/n^5 - 2939/n^6 - ...
MATHEMATICA
Flatten[{1, Table[Sum[CoefficientList[Assuming[Element[x, Reals], Series[E^(4/x)*x^4/ExpIntegralEi[1/x]^4, {x, 0, 25}]], x][[k+1]] * StirlingS2[n-1, k-1], {k, 1, n}], {n, 1, 25}]}]
CROSSREFS
KEYWORD
sign
AUTHOR
Vaclav Kotesovec, Aug 12 2015
STATUS
approved