login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A025283 Composites that use the same digits as their prime factorization. 15

%I #17 Jun 29 2017 00:02:12

%S 25,121,1255,2349,5120,12337,12955,17482,25105,41323,43375,93217,

%T 100255,101299,105295,107329,117067,124483,127417,129595,132565,

%U 145273,146137,149782,163797,174082,174298,174793,174982,191239,250105,256315,263155

%N Composites that use the same digits as their prime factorization.

%C 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

%C 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

%H Giovanni Resta, <a href="/A025283/b025283.txt">Table of n, a(n) for n = 1..10000</a>

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

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

%K base,nonn

%O 1,1

%A _David W. Wilson_

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 20 00:26 EDT 2024. Contains 371798 sequences. (Running on oeis4.)