A063248 Smallest composite number in base n which contains its largest proper factor as a substring.

4, 9, 407, 25, 9, 49, 893, 1387, 15, 121, 23533, 169, 21, 4717, 10579, 289, 27, 361, 25, 49, 33, 529, 32437, 61903, 39, 24523, 35, 841, 45, 961, 39917, 77, 51, 64993, 111277, 1369, 57, 91, 99101, 1681, 49, 1849, 55, 108389, 69, 2209, 207133, 139163

Offset: 2

Author

Robert G. Wilson v, Aug 08 2001

Keywords

• base
• nonn

Crossrefs

Cf. A062238.

Programs

Mathematica

sublist[ s_, l_ ] := Module[ {i, ls=Length[ s ]}, For[ i=1, i+ls-1<=Length[ l ], i++, If[ s==Take[ l, {i, i+ls-1} ], Return[ True ] ] ]; False ]; a[ n_ ] := Module[ {k}, For[ k=4, True, k++, If[ !PrimeQ[ k ]&&sublist[ IntegerDigits[ Divisors[ k ][ [ -2 ] ], n ], IntegerDigits[ k, n ] ], Return[ k ] ] ] ];

Extensions

More terms from Dean Hickerson, Aug 10 2001