%I #10 Jun 02 2019 18:20:05
%S 2,2,4,9,32,135,768,5145,40704,363825,3632640,39927195,479047680,
%T 6227155935,87178936320,1307676395025,20922800209920,355687462555425,
%U 6402373891522560,121645101063561075,2432902011892531200,51090942185458750575,1124000727859357286400
%N n! + n!!.
%e 5! = 120 and 5!! = 15, so a(5) = 135.
%t Table[n!+n!!,{n,0,30}]
%Y A000142(n)+A006882(n).
%K nonn,easy
%O 0,1
%A _Harvey P. Dale_, May 26 2019