A154931 Third column of A154921.

1, 3, 18, 130, 1125, 11361, 131124, 1702548, 24562575, 389799355, 6748339158, 126565340694, 2556332651145, 55320126580005, 1276961156453160, 31318513972988008, 813295166343147315, 22293401161982239071, 643251586018800611370, 19488333337058966337930

Offset

2,2

Links

Alois P. Heinz, Table of n, a(n) for n = 2..424

Formula

E.g.f.: 1/2!*x^2/(2-exp(x)) = x^2/2! + 3*x^3/3! + 18*x^4/4! + .... - Peter Bala, Apr 20 2012

Maple

b:= proc(n, p) option remember; `if`(n=0, p!,
      add(b(n-j, p+j)/j!, j=1..n))
    end:
a:= n-> b(n-2, 2)/2:
seq(a(n), n=2..23);  # Alois P. Heinz, Feb 03 2019

Mathematica

With[{nn=20}, Drop[CoefficientList[Series[(x^2/2)/(2-Exp[x]), {x, 0, nn}], x] Range[0, nn]!, 2]] (* Harvey P. Dale, Jan 16 2013 *)

Crossrefs

Cf. A154921.

Sequence in context: A365134 A171805 A368963 * A362704 A047731 A291841

Adjacent sequences: A154928 A154929 A154930 * A154932 A154933 A154934

Keyword

nonn,easy

Author

Mats Granvik, Jan 17 2009

Extensions

a(9) through a(18) from Peter Bala, Apr 20 2012

a(19)-a(21) from Alois P. Heinz, Feb 03 2019

Status

approved