A107404 - OEIS

%I #9 Jun 27 2013 07:32:02

%S 1,2,6,26,144,962,7536,67706,685824,7730882,95970816,1300815386,

%T 19113775104,302616787202,5135568746496,92996021795066,

%U 1789758460329984,36479831022049922,785020114093080576,17785273588395966746

%N E.g.f. = 1/(1-sinh(x))^2

%F a(n) = D^n(1/(1-x)^2) evaluated at x = 0, where D is the operator sqrt(1+x^2)*d/dx. Cf. A006154. - Peter Bala, Dec 06 2011

%F a(n) ~ n!*n/(2*(log(1+sqrt(2)))^(n+2)). - _Vaclav Kotesovec_, Jun 27 2013

%p E(x):=1/(1-sinh(x))^2: f[0]:=E(x): for n from 1 to 30 do f[n]:=diff(f[n-1],x) od: x:=0: seq(f[n],n=0..30);

%t CoefficientList[Series[1/(1-Sinh[x])^2, {x, 0, 20}], x]* Range[0, 20]! (* _Vaclav Kotesovec_, Jun 27 2013 *)

%Y Cf. A000557. A006154.

%K nonn

%O 0,2

%A _Miklos Kristof_, Jun 09 2005