A193072 Odd numbers N for which numerator(sigma(N^2)/N^2) is prime but sigma(N^2) is composite.
39, 507, 2379, 6591, 13167, 29511, 148955, 1672209, 8852259, 212370543, 1929229929
Offset: 1
Links
- Lucas A. Brown, A193072.py
Programs
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PARI
forstep(N=1, 1e7, 2, isprime(numerator(sigma(N^2)/N^2)) && !isprime(sigma(N^2)) && print1(N", "))
Extensions
a(8)-a(10) from Donovan Johnson, Sep 19 2011
a(11) from Lucas A. Brown, Apr 12 2021
Comments