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A056612 a(n) = gcd(n!, n!(1 + 1/2 + 1/3 + ... + 1/n)). 4
1, 1, 1, 2, 2, 36, 36, 144, 144, 1440, 1440, 17280, 17280, 241920, 3628800, 29030400, 29030400, 1567641600, 1567641600, 156764160000, 9876142080000, 217275125760000, 217275125760000, 1738201006080000, 1738201006080000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

The first difference between this sequence and A131657 occurs for n=20, while the first difference between this sequence and A131658 occurs for n=21. - Christian Krattenthaler (christian.krattenthaler(AT)univie.ac.at), Sep 30 2007

LINKS

Michael De Vlieger, Table of n, a(n) for n = 1..535

FORMULA

a(n) = A000142(n)/A002805(n) = A000254(n)/A001008(n). - Franz Vrabec, Sep 13 2005

EXAMPLE

a(4) = gcd(4!, 4!(1 + 1/2 + 1/3 + 1/4)) = gcd(24, 50) = 2.

MATHEMATICA

Table[GCD[#, # Total@ Map[1/# &, Range@ n]] &[n!], {n, 25}] (* Michael De Vlieger, Sep 23 2017 *)

CROSSREFS

Cf. A007757, A131657, A131658.

Sequence in context: A297795 A024176 A286375 * A131658 A131657 A267345

Adjacent sequences:  A056609 A056610 A056611 * A056613 A056614 A056615

KEYWORD

easy,nonn

AUTHOR

Leroy Quet, Aug 08 2000

STATUS

approved

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Last modified January 20 10:19 EST 2018. Contains 297960 sequences.