A117735 - OEIS

%I #3 Mar 30 2012 17:34:20

%S 0,0,0,0,18,90,690,4830,40110,362670,3628590,39914490,478999290,

%T 6226990770,87178261170,1307674337970,20922789857970,355687427585490,

%U 6402373705217490,121645100399132310,2432902008166940310

%N a(n) = n! - primorial(n).

%F a(0)=0. a(n) = n!-A034386(n) = A000142(n)-A034386(n), n>0.

%t f[n_] := If[PrimeQ[n] == True, 1, n] cf[0] = 1; cf[n_Integer?Positive] := cf[n] = f[n]*cf[n - 1] g[n_] := If[PrimeQ[n] == True, n, 1] p[0] = 1; p[n_Integer?Positive] := p[n] = g[n]*p[n - 1] Table[n! - p[n], {n, 0, 20}]

%Y Cf. A034386, A117683.

%K nonn

%O 0,5

%A _Roger L. Bagula_, Apr 14 2006