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A063132 Composite numbers not divisible by 2 or 3 which in base 3 contain their largest proper factor as a substring. 1

%I

%S 49,427,671,949,1387,1679,1849,2117,3397,3829,4307,6017,6169,7141,

%T 8299,10547,11773,13703,17161,17819,19517,24523,25019,25877,29941,

%U 30607,31459,33853,34447,34547,35657,35947,38243,38491,38579,39283,45571

%N Composite numbers not divisible by 2 or 3 which in base 3 contain their largest proper factor as a substring.

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

%Y Cf. A063127, A062238.

%K base,nonn

%O 1,1

%A _Robert G. Wilson v_, Aug 08 2001

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Last modified October 1 02:38 EDT 2022. Contains 357134 sequences. (Running on oeis4.)