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A055489
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Largest number x such that sum of divisors of x is n!.
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5
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5, 23, 95, 719, 5039, 39917, 361657, 3624941, 39904153, 479001599, 6226862869, 87178291199, 1307672080867, 20922780738961, 355687390376431, 6402373545694717, 121645099711277873, 2432902005056589697, 51090942157413850441
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,1
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COMMENTS
| For n = 1, a(1) = 1; for n = 2 there is no solution.
For n in A002982, a(n) = n!-1.
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REFERENCES
| R. K. Guy (1981): Unsolved Problems In Number Theory, B39.
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LINKS
| Ray Chandler, Table of n, a(n) for n=3..52
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FORMULA
| a(n) = Max{x; Sigma[x] = n!} = Max{x; A000203(x) = A000142(n)}
a(n) = A057637(A000142(n)). - Chandler
a(A002982(n)) = A000142(A002982(n)) - 1. - Chandler
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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}
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CROSSREFS
| Cf. A000203, A000142, A055486, A055488.
Sequence in context: A146013 A028894 A140529 * A109765 A119012 A084615
Adjacent sequences: A055486 A055487 A055488 * A055490 A055491 A055492
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Jun 28 2000
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EXTENSIONS
| More terms from Jud McCranie (JudMcCranie(AT)ugaalum.uga.edu), Oct 09 2000
a(15) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Aug 31 2008
a(16)-a(19) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Nov 22 2008
a(20)-a(52) from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 15 2009
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