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

1,2

Links

Table of n, a(n) for n=1..50.

Prog

(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

Crossrefs

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

Sequence in context: A243811 A194073 A023496 * A176003 A216880 A144730

Adjacent sequences: A191865 A191866 A191867 * A191869 A191870 A191871

Keyword

nonn,less

Author

Juri-Stepan Gerasimov, Jun 18 2011

Extensions

More terms from Charles R Greathouse IV, Jun 19 2011

Status

approved