OFFSET
0,2
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..420
FORMULA
a(k) ~ -k! / (2 * (log(2))^(k+1)).
For n>0, Sum_{k=1..n} a(k) * Stirling1(n-1, k-1) = A259472(n). - Vaclav Kotesovec, Aug 03 2015
For n>0, a(n) = Sum_{k=1..n} A259472(k) * Stirling2(n-1, k-1). - Vaclav Kotesovec, Aug 03 2015
EXAMPLE
A003319(n) / n! ~ 1 - 2/n - 1/n^2 - 5/n^3 - 32/n^4 - 253/n^5 - 2381/n^6 - ...
MATHEMATICA
Flatten[{1, Table[Sum[Assuming[Element[x, Reals], SeriesCoefficient[E^(2/x)*x^2 / ExpIntegralEi[1/x]^2, {x, 0, k}]] * StirlingS2[n-1, k-1], {k, 1, n}], {n, 1, 20}]}] (* Vaclav Kotesovec, Aug 03 2015 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Vaclav Kotesovec, Jul 27 2015
STATUS
approved