OFFSET
1,1
COMMENTS
Numbers k such that k and sigma(4*k^2) are not coprime, sigma = A000203.
LINKS
Jianing Song, Table of n, a(n) for n = 1..12241 (all terms <= 40000)
FORMULA
a(n) = A356452(n)/2.
EXAMPLE
7 is a term since 7 and sigma(4*7^2) = 399 have a common factor 7.
PROG
(PARI) isA356454(n) = gcd(n, sigma(4*n^2))>1
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jianing Song, Aug 07 2022
STATUS
approved