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A014454
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Sum_{1<=k<n} gcd(k!,n!/k!).
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2
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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
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OFFSET
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1,3
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LINKS
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EXAMPLE
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a(5) = gcd(1!,5!)+gcd(2!,3*4*5)+gcd(3!,4*5)+gcd(4!,5)=1+2+2+1 = 6.
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PROG
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(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
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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