A225362 Numbers n with the property that there are integers k, h such that sigma(n) = k^tau(n) = tau(n)^h.

1, 3, 217, 3937, 57337, 917497, 1040257, 11010027, 12189603, 16252897, 16646017, 3612185689, 4294434817, 66571993057, 68718821377, 17590038552577, 270545999761249, 281472829095937, 16138807601873739769, 16140901064495857657, 292842062170139131777, 1208766717309082486038529

Offset

1,2

Comments

Intersection of A225239 and A051281.

Links

Table of n, a(n) for n=1..22.

Example

3937 is a term because sigma(3937) = 4096 = 8^tau(3937) = 8^4 = tau(3937)^6 = 4^6; k = 8, h = 6.

Crossrefs

Cf. A000005 (tau=number of divisors), A000203 (sigma=sum of divisors).

Cf. A225239, A051281.

Sequence in context: A300037 A342234 A225239 * A373055 A063836 A172811

Adjacent sequences: A225359 A225360 A225361 * A225363 A225364 A225365

Keyword

nonn

Author

Jaroslav Krizek, May 05 2013

Extensions

More terms, using A051281 b-file, from Michel Marcus, Feb 19 2020

Status

approved