A014454 Sum_{1<=k

0, 1, 2, 5, 6, 21, 22, 73, 210, 1693, 1694, 2097, 2098, 12997, 21468, 174169, 174170, 1986237, 1986238, 10178833, 16875654, 246551437, 246551438, 2032266537, 3767596738, 45445808989, 260705796192, 2932954933753, 2932954933754, 5496591783573, 5496591783574

Offset: 1

Author

Reinhard Zumkeller, Feb 12 2002

Keywords

• nonn

Examples

			a(5) = gcd(1!,5!)+gcd(2!,3*4*5)+gcd(3!,4*5)+gcd(4!,5)=1+2+2+1 = 6.
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A000142.

Cf. A166350.

Programs

Haskell

a014454 n = sum $ zipWith gcd kfs $ map (div nf) kfs
   where (nf:kfs) = reverse $ a166350_row n
-- Reinhard Zumkeller, Nov 11 2013

PARI

a(n) = sum(k=1, n-1, gcd(k!, n!/k!)); \\ Michel Marcus, Aug 04 2013