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