%I #22 Apr 18 2020 02:00:38
%S 1,125,17692313
%N Nonprime numbers whose divisors all appear as a substring in the number's decimal expansion.
%C This is the subsequence of A239058 without the primes having a digit 1, A208270. It is thus a subsequence of A092911 (all divisors can be formed using the digits of the number) which is a subsequence of A011531 (numbers having the digit 1).
%C The term a(3)=17692313=A239058(870356), as well as the numbers 4482669527413081, 21465097175420089, and 567533481816008761 which are also members, were found by _Charles R Greathouse IV_, Mar 09 2014
%C The square of any term of A115738 is a member of this sequence. The above larger examples are of that form.
%C a(4) > 10^12. - _Giovanni Resta_, Sep 08 2018
%H Giovanni Resta, <a href="/A239060/a239060.txt">Terms of the form p*q, with p and q primes, p < 50000, q < 10^100</a>
%H <a href="/index/De#decimal_expansion">Index entries for sequences related to decimal expansion of n</a>
%e The divisors of 17692313 are {1, 23, 769231, 17692313}; it can be seen that all of them occur as a substring in 17692313, therefore 17692313 is in this sequence.
%o (PARI) is(n)=!isprime(n)&&is_A239058(n)
%o (PARI) overlap(long,short)=my(D=10^#digits(short)); while(long>=short, if(long%D==short,return(1));long\=10); 0
%o is(n)=my(d=divisors(n)); #d!=2 && !forstep(i=#d-1,1,-1, if(!overlap(n,d[i]), return(0))) \\ _Charles R Greathouse IV_, Mar 09 2014
%Y Cf. A092911, A011531, A121041, A121022-A121040, A018834.
%K nonn,base,bref,more
%O 1,2
%A _M. F. Hasler_, Mar 09 2014