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n! + n!!.
0

%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