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.
%I A185867 #11 Jan 21 2022 23:31:17 %S A185867 2,4,5,6,8,15,18,20,25,35,40,45,50,60,75,80,125,150,175,180,200,225, %T A185867 250,275,350,375,400,450,475,500,575,600,625,675,750,800,875,1125, %U A185867 1250,1375,1500,1625,1750,1800,1875 %N A185867 Numbers m whose decimal digits are a subsequence of the decimal digits of k*m for some 1 < k < 10. %C A185867 Are there finitely many non-multiples of 10 in this sequence? a(72) = 7875 seems to be the last one. - _Charles R Greathouse IV_, Feb 08 2011 %e A185867 15 is a term because 15*7 = 105, and 105 can be formed from 15 by inserting the digit 0 in the middle. %o A185867 (PARI) sub(v,u)=my(j=1);if(#v==#u,return(0));for(i=1, #v, if(v[i]!=u[j],if(i!=j,return(0)),j++));1 %o A185867 isA185867(n)=my(N=eval(Vec(Str(n))));for(k=2, 9, if(sub(eval(Vec(Str(n*k))),N),return(k)));0 %K A185867 nonn,base %O A185867 1,1 %A A185867 _Paul Richards_, Feb 05 2011 %E A185867 Program and a(22)-a(45) from _Charles R Greathouse IV_, Feb 08 2011