cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A340916 Integers m that have at least one divisor d such that d+m/d is a substring of m.

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%I A340916 #8 Jan 27 2021 05:34:12
%S A340916 4,272,352,400,414,418,425,432,448,450,465,490,504,518,572,585,598,
%T A340916 720,732,744,756,768,972,1092,1104,1152,1210,1221,1232,1243,1254,1265,
%U A340916 1276,1287,1298,1309,1792,1872,1887,1890,1904,1914,1920,1950,1972,2100,2112,2672
%N A340916 Integers m that have at least one divisor d such that d+m/d is a substring of m.
%C A340916 These are the resulting product strings in A339144.
%e A340916 272 = 4*68 contains 4+68 = 72 as a substring, so 272 is a term.
%t A340916 q[n_] := AnyTrue[Divisors[n], SequenceCount[IntegerDigits[n], IntegerDigits[# + n/#]] > 0 &]; Select[Range[3000], q] (* _Amiram Eldar_, Jan 26 2021 *)
%o A340916 (PARI) isok(n) = {fordiv(n, d, if (#strsplit(Str(n), Str(d+n/d)) > 1, return(1)); if (d^2 > n, return(0)););}
%Y A340916 Cf. A339144, A340917.
%K A340916 nonn,base
%O A340916 1,1
%A A340916 _Michel Marcus_, Jan 26 2021