login
The OEIS is supported by
the many generous donors to the OEIS Foundation
.
A359167
Numbers k for which there is an even number of prime factors (when counted with multiplicity) in k*sigma(k), where sigma is the sum of divisors function.
3
1, 2, 7, 11, 12, 14, 15, 17, 19, 20, 22, 24, 29, 30, 31, 32, 34, 36, 38, 39, 40, 41, 43, 45, 47, 48, 49, 52, 58, 62, 65, 67, 69, 71, 72, 75, 77, 78, 79, 80, 81, 82, 84, 86, 90, 92, 94, 97, 98, 100, 101, 104, 105, 107, 108, 109, 111, 113, 115, 117, 119, 121, 127, 128, 130, 132, 133, 134, 135, 137, 138
(
list
;
graph
;
refs
;
listen
;
history
;
text
;
internal format
)
OFFSET
1,2
COMMENTS
Numbers k such that the parities of
A001222
(k) and
A058063
(k) are equal.
LINKS
Table of n, a(n) for n=1..71.
Index entries for sequences related to sigma(n)
PROG
(PARI) isA359167(n) = !((bigomega(n)+bigomega(sigma(n)))%2);
CROSSREFS
Positions of 1's in
A359166
.
Cf.
A000203
,
A001222
,
A058063
,
A359168
(complement).
Sequence in context:
A226089
A208846
A087723
*
A299242
A184792
A136998
Adjacent sequences:
A359164
A359165
A359166
*
A359168
A359169
A359170
KEYWORD
nonn
AUTHOR
Antti Karttunen
, Dec 19 2022
STATUS
approved
