%I #13 Aug 15 2020 16:02:10
%S -2,1,1,9,72,792,10512,165168,2992608,61445088,1409857920,35751525120,
%T 992877886080,29970166769280,976990865518080,34206887786803200,
%U 1280236466132467200,51004766655793036800,2155155171665039308800
%N a(n+2) = (2n+3)*a(n+1) + (n+1)^2*a(n).
%H K. S. Brown, <a href="https://www.mathpages.com/home/kmath381/kmath381.htm">Integer Sequences Related To Pi</a>
%t RecurrenceTable[{a[0]==-2,a[1]==1,a[n+2]==(2n+3)a[n+1]+(n+1)^2 a[n]},a,{n,20}] (* _Harvey P. Dale_, Dec 31 2017 *)
%K sign,easy
%O 0,1
%A _N. J. A. Sloane_, May 26 2000
%E More terms from _James A. Sellers_, May 27 2000