A025283 Composites that use the same digits as their prime factorization.

25, 121, 1255, 2349, 5120, 12337, 12955, 17482, 25105, 41323, 43375, 93217, 100255, 101299, 105295, 107329, 117067, 124483, 127417, 129595, 132565, 145273, 146137, 149782, 163797, 174082, 174298, 174793, 174982, 191239, 250105, 256315, 263155

Offset: 1

Author

David W. Wilson

Keywords

• base
• nonn

Comments

Here exponents equal to 1 are not taken into account, so 1255 = 5^1*251^1 = 5*251 is a term. Prime numbers are excluded because they all trivially use the same digits as their prime factorization. If, on the contrary, exponents equal to 1 are counted, the resulting sequence is A075047. - Giovanni Resta, Jul 14 2015

An interesting example of the factorization digits appearing in the same order as in its composite generator: 13532385396179 = 13 * 53^2 * 3853 * 96179. - Hans Havermann, Jun 28 2017

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A075047, A260046, A260047, A260048, A260049, A260050, A260051, A260052, A260053, A260054, A260055.

Programs

Mathematica

Select[Range[10^5], !PrimeQ@ # && Sort@ IntegerDigits@ # == Sort@ Flatten@ IntegerDigits@ Select[ Flatten@ FactorInteger@ #, #>1 &] &] (* Giovanni Resta, Jul 14 2015 *)