|
Search: id:A055489
|
|
|
| A055489 |
|
Largest number x such that sum of divisors of x is n!. |
|
+0
3
|
|
| 5, 23, 95, 719, 5039, 39917, 361657, 3624941, 39904153, 479001599, 6226862869, 87178291199, 1307672080867, 20922780738961, 355687390376431, 6402373545694717, 121645099711277873, 2432902005056589697, 51090942157413850441
(list; graph; listen)
|
|
|
OFFSET
|
3,1
|
|
|
COMMENT
|
For n = 1, a(1) = 1; for n = 2 there is no solution. Special maximal solutions are the cases when x = n!-1 = prime.
|
|
REFERENCES
|
R. K. Guy (1981): Unsolved Problems In Number Theory, B39.
|
|
LINKS
|
Ray Chandler, Table of n, a(n) for n=3..52
|
|
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
|
|
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
|
Cf. A000203, A000142, A055486, A055488.
Sequence in context: A146013 A028894 A140529 this_sequence A109765 A119012 A084615
Adjacent sequences: A055486 A055487 A055488 this_sequence A055490 A055491 A055492
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu), Jun 28 2000
|
|
EXTENSIONS
|
More terms from Jud McCranie (j.mccranie(AT)comcast.net), 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
|
|
|
Search completed in 0.002 seconds
|
