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%I #13 Dec 26 2022 13:04:56
%S 15,25,125,1537,3977,11371,38117,110317,117197,123679,143323,146137,
%T 179297,197513,316619,390913,397139,399797,485357,779917,797191,
%U 990919,1110691,1178951,1483117,1723717,1813733,2165299,2273099,2369777,2947969,3035171,3099013,3183113
%N Composite numbers which contain their largest proper divisor as a substring.
%H Michel Marcus, <a href="/A062238/b062238.txt">Table of n, a(n) for n = 1..272</a>
%e 3{97}7 = 97*41.
%t Do[ If[ !PrimeQ[ n ] && StringPosition[ ToString[ n ], ToString[ Divisors[ n ] [ [ -2 ] ] ] ] != {}, Print[ n ] ], {n, 2, 10^7} ]
%t Select[Range[319*10^4],CompositeQ[#]&&SequenceCount[IntegerDigits[ #],IntegerDigits[ Divisors[#][[-2]]]]>0&] (* _Harvey P. Dale_, Dec 26 2022 *)
%o (PARI) gpd(n) = if(n==1, 1, n/factor(n)[1, 1]); \\ A032742
%o issub(vv, v) = {for (i=1, #v - #vv + 1, if (vector(#vv, k, v[k+i-1]) == vv, return(1)););}
%o isok(n) = if ((n>1) && !isprime(n), issub(digits(gpd(n)), digits(n))); \\ _Michel Marcus_, Dec 31 2020
%Y Cf. A002808 (composite numbers), A032742.
%K base,nonn
%O 1,1
%A _Erich Friedman_, Jun 30 2001
%E More terms from _Robert G. Wilson v_, Aug 08 2001
%E More terms from _Michel Marcus_, Dec 31 2020
%E Clarified definition at the suggestion of _Harvey P. Dale_. - _N. J. A. Sloane_, Dec 26 2022
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