%I #7 Dec 18 2017 04:15:17

%S 0,1,4,14,52,220,1092,6388,43588,341444,3022660,29835844,324782916,

%T 3864151876,49875956548,694041238340,10356520497988,164956188717892,

%U 2793150548587332,50100649026499396,948943120107352900,18925792541725471556,396439630395708060484

%N a(n) = e^2 * Sum_{k=0..n-1} Gamma(k + 1, 2).

%F a(n) = (2*n-4)*a(n-3)+(3-3*n)*a(n-2)+(2+n)*a(n-1) for n >= 3.

%p a := proc(n) option remember; if n=0 then 0 elif n=1 then 1 elif n=2 then 4 else

%p (2*n-4)*a(n-3)+(3-3*n)*a(n-2)+(2+n)*a(n-1) fi end: seq(a(n), n=0..22);

%t a[n_] := E^2 Sum[Gamma[k + 1, 2], {k,0,n-1}]; Table[a[n], {n,0,22}]

%Y Cf. A010842.

%K nonn

%O 0,3

%A _Peter Luschny_, Dec 17 2017