A187942 Numbers n of the form (product of divisors of k)/(sum of divisors of k) for some k.

1, 3, 392, 11250, 131769, 501126, 15780962, 131079601, 1568294784, 30261936128, 2966827112704, 119439360000000, 238660389865072, 6566468639062500, 39226324511250000, 73141605808805632, 162778775259375000, 282080144308712092

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Prog

(PARI) A007955(n)=if(issquare(n, &n), n^numdiv(n^2), n^(numdiv(n)/2))
v=[]; for(n=1, 1e4, if(a(n)%sigma(n)==0, v=concat(v, A007955(n)/sigma(n)))); vecsort(v, , 8) \\ Charles R Greathouse IV, Mar 16 2011

Crossrefs

Cf. A000203, A007955.

Sequence in context: A193131 A193154 A120061 * A244670 A199146 A137023

Adjacent sequences: A187939 A187940 A187941 * A187943 A187944 A187945

Keyword

nonn

Author

Juri-Stepan Gerasimov, Mar 16 2011

Extensions

a(5)-a(18) from Charles R Greathouse IV, Mar 16 2011

Status

approved