OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..170
FORMULA
a(n) ~ 2 * (n-1)! * (1 + 3/n + 12/n^2 + 58/n^3 + 327/n^4 + 2107/n^5 + 15329/n^6 + 125041/n^7 + 1139467/n^8 + 11582187/n^9 + 131230827/n^10). - Vaclav Kotesovec, Mar 17 2015
EXAMPLE
a(4) = 44 = (0, 6, 5, 3, 1) dot (1, 2, 3, 4, 5) = (0 + 12 + 15 + 12 + 5).
MAPLE
series((1-x*hypergeom([1, 1], [], x))^(-2), x=0, 50); # appears to generate the sequence - Mark van Hoeij, Apr 22 2013
MATHEMATICA
CoefficientList[Series[1/(1-x*HypergeometricPFQ[{1, 1}, {}, x])^2, {x, 0, 20}], x] (* Vaclav Kotesovec, Mar 17 2015 after Mark van Hoeij *)
CoefficientList[Assuming[Element[x, Reals], Series[E^(2/x)/(ExpIntegralEi[1/x]-E^(1/x))^2, {x, 0, 25}]], x] (* Vaclav Kotesovec, Aug 03 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Oct 22 2007, corrected Oct 26 2007
EXTENSIONS
More terms from Alois P. Heinz, Apr 27 2012
STATUS
approved