A134378 A084938 * [1,2,3,...], where A084938 is taken as lower triangular matrix.

1, 2, 5, 14, 44, 158, 663, 3310, 19759, 139660, 1147120, 10729684, 112309193, 1297522650, 16371057801, 223716758346, 3289199827236, 51745234494858, 867023125576027, 15411557297930534, 289610871340870883, 5736017561257017128, 119413599371241577016

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

Cf. A084938, A260532.

Sequence in context: A095148 A368636 A060996 * A101226 A240610 A149887

Adjacent sequences: A134375 A134376 A134377 * A134379 A134380 A134381

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