A154931 - OEIS

%I #17 Feb 03 2019 08:25:33

%S 1,3,18,130,1125,11361,131124,1702548,24562575,389799355,6748339158,

%T 126565340694,2556332651145,55320126580005,1276961156453160,

%U 31318513972988008,813295166343147315,22293401161982239071,643251586018800611370,19488333337058966337930

%N Third column of A154921.

%H Alois P. Heinz, <a href="/A154931/b154931.txt">Table of n, a(n) for n = 2..424</a>

%F 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

%p b:= proc(n, p) option remember; `if`(n=0, p!,

%p       add(b(n-j, p+j)/j!, j=1..n))

%p     end:

%p a:= n-> b(n-2, 2)/2:

%p seq(a(n), n=2..23);  # _Alois P. Heinz_, Feb 03 2019

%t 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 *)

%Y Cf. A154921.

%K nonn,easy

%O 2,2

%A _Mats Granvik_, Jan 17 2009

%E a(9) through a(18) from _Peter Bala_, Apr 20 2012

%E a(19)-a(21) from _Alois P. Heinz_, Feb 03 2019