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%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