A110377 a(n) = Sum_{r < n, gcd(r,n)=1} n!/r!.

1, 2, 9, 28, 205, 726, 8659, 47384, 562545, 4234330, 68588311, 483088332, 10699776685, 102434734598, 2016289908585, 24588487650736, 611171244308689, 6456997293606738, 209020565553571999, 2838875160624256460

Offset: 1

Author

Amarnath Murthy, Jul 24 2005

Keywords

• easy
• nonn

Examples

			a(6) = 6!(1/1! + 1/5!) = 726.
		

Crossrefs

Cf. A038048, A110276, A110373, A110374.

Programs

Maple

a:=proc(n) local s,r: s:=0: for r from 1 to n do if gcd(r,n)=1 then s:=s+1/r! else s:=s: fi: od: n!*s end: seq(a(n),n=1..23); # Emeric Deutsch, Jul 25 2005

Extensions

More terms from Emeric Deutsch, Jul 25 2005