A185867 Numbers m whose decimal digits are a subsequence of the decimal digits of k*m for some 1 < k < 10.

2, 4, 5, 6, 8, 15, 18, 20, 25, 35, 40, 45, 50, 60, 75, 80, 125, 150, 175, 180, 200, 225, 250, 275, 350, 375, 400, 450, 475, 500, 575, 600, 625, 675, 750, 800, 875, 1125, 1250, 1375, 1500, 1625, 1750, 1800, 1875

Offset

1,1

Comments

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

Links

Table of n, a(n) for n=1..45.

Example

15 is a term because 15*7 = 105, and 105 can be formed from 15 by inserting the digit 0 in the middle.

Prog

(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
isA185867(n)=my(N=eval(Vec(Str(n)))); for(k=2, 9, if(sub(eval(Vec(Str(n*k))), N), return(k))); 0

Crossrefs

Sequence in context: A110277 A325680 A176654 * A326910 A326905 A327061

Adjacent sequences: A185864 A185865 A185866 * A185868 A185869 A185870

Keyword

nonn,base

Author

Paul Richards, Feb 05 2011

Extensions

Program and a(22)-a(45) from Charles R Greathouse IV, Feb 08 2011

Status

approved