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A055488
Smallest number x such that sum of divisors of x is n!.
4
5, 14, 54, 264, 1560, 10920, 97440, 876960, 10263240, 112895640, 1348827480, 18029171160, 264370186080, 3806158356000, 62703141621120, 1128159304272000, 20422064875212000, 404757215566704000, 8208550091549808000, 177650747421074928000
OFFSET
3,1
COMMENTS
For n = 1, a(1) = 1; for n = 2, there is no solution.
REFERENCES
R. K. Guy (1981): Unsolved Problems In Number Theory, B39.
FORMULA
a(n) = Min{x; Sigma[x] = n!} = Min{x; A000203(x) = A000142(n)}
EXAMPLE
For n = 6 the 15 solutions are as follows: {264,270,280,354,376,406,418,435,459,478,537,623,649,667,719}
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Jun 28 2000
EXTENSIONS
More terms from Jud McCranie, Oct 09 2000
a(13), a(14) from Vim Wenders, Nov 06 2006, Jan 12 2007
a(15), a(16) from Donovan Johnson, Aug 26 2008, Mar 26 2010
a(17)-a(22) from Max Alekseyev, Jan 25 2012
STATUS
approved