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A014454 Sum_{1<=k<n} gcd(k!,n!/k!). 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
EXAMPLE
a(5) = gcd(1!,5!)+gcd(2!,3*4*5)+gcd(3!,4*5)+gcd(4!,5)=1+2+2+1 = 6.
PROG
(PARI) a(n) = sum(k=1, n-1, gcd(k!, n!/k!)); \\ Michel Marcus, Aug 04 2013
(Haskell)
a014454 n = sum $ zipWith gcd kfs $ map (div nf) kfs
where (nf:kfs) = reverse $ a166350_row n
-- Reinhard Zumkeller, Nov 11 2013
CROSSREFS
Cf. A000142.
Cf. A166350.
Sequence in context: A248719 A184594 A341756 * A136324 A128367 A178924
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 12 2002
STATUS
approved

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Last modified May 20 03:57 EDT 2024. Contains 372703 sequences. (Running on oeis4.)