A110379 - OEIS

%I #7 Sep 03 2017 03:31:05

%S 1,5,31,217,1737,15634,156341,1719751,20637013,268281169,3755936367,

%T 56339045506,901424728097,15324220377649,275835966797683,

%U 5240883369155977,104817667383119541,2201171015045510362

%N a(n) = Sum_{composite c <= n} n!/c!.

%e a(6) = 6!(1/4! + 1/6!) = 31.

%p a:=proc(n) local s,i :s:=0: for i from 4 to n do if isprime(i)=false then s:=s+1/i! else s:=s: fi od: n!*s; end; seq(a(n),n=4..24); # _Emeric Deutsch_, Jul 25 2005

%Y Cf. A038048, A110373, A110374, A110376, A110377, A110378.

%K easy,nonn

%O 4,2

%A _Amarnath Murthy_, Jul 24 2005

%E More terms from _Emeric Deutsch_, Jul 25 2005