|
|
A325654
|
|
Numbers m with a divisor d satisfying sigma(d) = 2*m.
|
|
2
|
|
|
6, 28, 496, 8128, 60480, 65520, 4357080, 33550336, 47139840, 91065600, 285981696, 2758909440, 8589869056, 87722956800, 132867440640, 137438691328, 306007080960, 806062473216, 1409150457792, 363485766938112, 12177456042320640, 29884246553283840
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
Even perfect numbers from A000396 are terms.
|
|
LINKS
|
|
|
EXAMPLE
|
60480 is a term because 30240 divides 60480 and sigma(30240) = 120960 = 2*60480.
|
|
PROG
|
(Magma) [n: n in [1..100000] | #[d: d in Divisors(n) | SumOfDivisors(d) eq 2*n] gt 0]
(PARI) isok(n) = fordiv(n, d, if (sigma(d) == 2*n, return(1))); 0; \\ Michel Marcus, May 12 2019
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|