|
| |
|
|
A114887
|
|
Multiperfect numbers sigma(n)=k*n, which are divisible by the sum of their prime factors without repetition.
|
|
3
| |
|
|
120, 672, 32760, 2178540, 1379454720, 14182439040, 518666803200, 30823866178560, 71065075104190073088, 154345556085770649600, 9186050031556349952000, 680489641226538823680000
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| From a list of about 5000 multiperfect numbers, 38 numbers were found with the property, all having k<=9, the largest was the only one having k=9. A091443 uses sofpr with repetition. Conjecture: the sequence is finite.
|
|
|
LINKS
| Sven Simon, Table of n, a(n) for n = 1..38 [Conjectured to be complete]
Achim Flammenkamp, The Multiply Perfect Numbers Page (See here for the latest information about the search)
Eric Weisstein's World of Mathematics, Multiperfect numbers
|
|
|
EXAMPLE
| a(0) = 120 = 2^3*3*5, sofpr(120) = 2+3+5 = 10.
|
|
|
CROSSREFS
| Cf. A091443.
Sequence in context: A090216 A113546 A166069 * A069085 A039688 A005820
Adjacent sequences: A114884 A114885 A114886 * A114888 A114889 A114890
|
|
|
KEYWORD
| fini,nonn,changed
|
|
|
AUTHOR
| Sven Simon (sven-h.simon(AT)t-online.de), Feb 19 2006
|
| |
|
|
