|
| |
|
|
A272883
|
|
Numbers n such that sigma_k(x) = n has no solution for any k > 0.
|
|
1
|
|
|
|
2, 11, 16, 19, 22, 23, 25, 27, 29, 34, 35, 37, 41, 43, 45, 46, 47, 49, 51, 52, 53, 55, 58, 59, 61, 64, 66, 67, 69, 70, 71, 75, 76, 77, 79, 81, 83, 86, 87, 88, 89, 92, 94, 95, 97, 99, 100, 101, 103, 105, 106, 107, 109, 111, 113, 115, 116, 117, 118, 119, 123, 125
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
Recall that sigma_k(n) = Sum_{d|n} d^k.
Sigma_0(n), the number of divisors of n, can be any positive integer and so is ignored in this sequence.
Numbers n such that A271606(n) = 0.
|
|
|
LINKS
|
|
|
|
PROG
|
(Magma) [n: n in [1..2^7] | [n] notsubset Set(Sort([DivisorSigma(k, n): n in [1..2^7+1], k in [1..2^7+1] | DivisorSigma(k, n) lt 2^7+1]))]
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
