A063889 Composite numbers not divisible by 5 which in base 5 contain their largest proper factor as a substring.

4087, 5083, 5731, 8857, 10841, 11983, 15109, 18631, 27317, 29593, 49883, 52319, 61903, 62317, 65509, 67237, 80371, 87707, 89351, 101971, 108781, 114313, 121801, 129739, 136921, 140033, 143231, 147923, 158497, 167477, 186911, 199841, 202537

Offset: 1

Author

Robert G. Wilson v, Aug 27 2001

Keywords

• nonn

Programs

Mathematica

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} ]