%I #7 Aug 11 2016 17:00:36
%S 1,0,1,5,27,129,761,5137,40695,363815,3632629,39927183,479047667,
%T 6227155921,87178936305,1307676395009,20922800209903,355687462555407,
%U 6402373891522541,121645101063561055,2432902011892531179
%N a(n) = n! + n!! - n - 1.
%t Table[n! + n!! - n - 1, {n, 0, 20}] (* _Bruno Berselli_, Aug 11 2016 *)
%Y Cf. A006882, A110903, A128882.
%K nonn,easy
%O 0,4
%A _Olivier GĂ©rard_, Aug 01 2016