OFFSET
1,2
COMMENTS
Numbers k such that k and sigma(4*k^2) are coprime, sigma = A000203.
LINKS
Jianing Song, Table of n, a(n) for n = 1..7127 (all terms <= 10000)
FORMULA
a(n) = A356448(n)/2.
EXAMPLE
12 is a term since 12 and sigma(4*12^2) = 1651 are coprime.
PROG
(PARI) isA356450(n) = gcd(n, sigma(4*n^2))==1
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jianing Song, Aug 07 2022
STATUS
approved