



1, 3, 53, 2119, 148329, 16019531, 2467007773, 513137616783, 138547156531409, 47106033220679059, 19690321886243846661, 9923922230666898717143, 5934505493938805432851513, 4154153845757163802996059099
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OFFSET

0,2


LINKS

Table of n, a(n) for n=0..13.


FORMULA

a(n) = (2*n + 1)!*hypergeom([2*n], [2*n  1], 1).  Peter Luschny, Nov 02 2018
Dfinite with recurrence a(n) +(4*n^22*n+1)*a(n1) +2*n*(2*n3)*a(n2)=0.  R. J. Mathar, Jul 27 2022


MAPLE

a := n > (2*n+1)!*hypergeom([2*n], [2*n1], 1):
seq(simplify(a(n)), n=0..13); # Peter Luschny, Nov 02 2018


MATHEMATICA

a[n_] := (2n)! SeriesCoefficient[E^x / (1x)^2, {x, 0, 2n}];
Table[a[n], {n, 0, 13}] (* JeanFrançois Alcover, Jun 11 2019 *)


CROSSREFS

Cf. A000255.
Sequence in context: A012742 A012823 A098932 * A300420 A300683 A296678
Adjacent sequences: A100441 A100442 A100443 * A100445 A100446 A100447


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane, Nov 21 2004


EXTENSIONS

More terms from Hugo Pfoertner, Nov 26 2004


STATUS

approved



