A191868 Numbers n such that (product of divisors of 2n) mod (sum of divisors of 2n) is equal to number of divisors of 2n.

1, 4, 7, 13, 19, 31, 37, 43, 61, 67, 73, 79, 97, 103, 109, 127, 139, 151, 157, 163, 181, 193, 199, 211, 223, 229, 241, 271, 277, 283, 307, 313, 331, 337, 349, 367, 373, 379, 397, 409, 421, 433, 439, 448, 457, 463, 487, 499, 523, 541

Offset: 1

Author

Juri-Stepan Gerasimov, Jun 18 2011

Keywords

• nonn
• less

Crossrefs

Cf. A000005, A000203, A007955, A016777, A187680.

Programs

PARI

is(n)=my(t=2*n,P=if(issquare(t,&t), t^numdiv(t^2),t^(numdiv(t)/2))); P%sigma(2*n)==numdiv(2*n) \\ Charles R Greathouse IV, Jun 19 2011

Extensions

More terms from Charles R Greathouse IV, Jun 19 2011