A063889 - OEIS

%I #4 Mar 30 2012 17:30:33

%S 4087,5083,5731,8857,10841,11983,15109,18631,27317,29593,49883,52319,

%T 61903,62317,65509,67237,80371,87707,89351,101971,108781,114313,

%U 121801,129739,136921,140033,143231,147923,158497,167477,186911,199841,202537

%N Composite numbers not divisible by 5 which in base 5 contain their largest proper factor as a substring.

%t Do[ If[ !PrimeQ[ n ] && Mod[ n, 5 ] != 0 && StringPosition[ ToString[ FromDigits[ IntegerDigits[ n, 5 ] ] ], ToString[ FromDigits[ IntegerDigits[ Divisors[ n ][ [ -2 ] ], 5 ] ] ] ] != {}, Print[ n ] ], {n, 3, 10^6} ]

%K nonn

%O 1,1

%A _Robert G. Wilson v_, Aug 27 2001