A240845 Numbers m equal to the product of all of their integral proper roots (defined as numbers k in the range 1 < k < m such that k^j = m for some j).

64, 729, 15625, 46656, 117649, 1000000, 1771561, 2985984, 4826809, 7529536, 11390625, 24137569, 34012224, 47045881, 64000000, 85766121, 113379904, 148035889, 191102976, 268435456, 308915776, 481890304, 594823321, 729000000, 887503681, 1291467969, 1544804416, 1838265625

Offset

1,1

Comments

Numbers of the form a^b where a is a number that is not a perfect power and b is a perfect number (equal to the sum of its divisors). In other words, A007916^A000396.

Links

Table of n, a(n) for n=1..28.

Example

64 is a term because its roots are 2, 4, and 8, and 2*4*8 = 64.

Crossrefs

Cf. A000396, A007916.

Sequence in context: A074154 A351604 A343286 * A153160 A113851 A046455

Adjacent sequences: A240842 A240843 A240844 * A240846 A240847 A240848

Keyword

nonn

Author

J. Lowell, Apr 13 2014

Extensions

More terms from Jinyuan Wang, Jun 19 2021

Status

approved