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

1,1

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

Mathematica

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

Crossrefs

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

Sequence in context: A198040 A141722 A090159 * A076433 A069668 A274785

Adjacent sequences: A025280 A025281 A025282 * A025284 A025285 A025286

Keyword

base,nonn

Author

David W. Wilson

Status

approved