A062525 - OEIS

%I #8 Dec 25 2019 23:11:41

%S 4,0,3,5,2,3,2,5,1,4,10,14,3,9,6,7,8,9,10,12,7,6,17,21,10,17,6,5,9,20,

%T 26,25,5,21,9,15,12,10,13,14,4,10,9,14,6,11,14,12,17,13,18,3,7,29,13,

%U 13,16,25,11,11,20,25,6,27,2,14,24,8,5,20,23,7,8,10,10,13

%N 8^a(n) is smallest power of 8 containing the string 'n'.

%H Robert Israel, <a href="/A062525/b062525.txt">Table of n, a(n) for n = 0..9999</a>

%p F:= proc(dmax) local R,count,x,N,L,d,i,v, p;

%p count:= 0: x:= 1/8: N:= 10^dmax:

%p for p from 0 while count < N do

%p   x:= 8*x;

%p   L:= convert(x,base,10);

%p   for d from 1 to min(dmax, nops(L)) do

%p     for i from 1 to nops(L)-d+1 do

%p       v:= add(L[j]*10^(j-i),j=i..i+d-1);

%p       if not assigned(R[v]) then count:= count+1; R[v]:= p fi

%p od od od;

%p seq(R[v],v=0..N-1);

%p end proc:

%p F(2); # _Robert Israel_, Dec 25 2019

%t Table[k = 0; While[ StringPosition[ ToString[8^k], ToString[n] ] == {}, k++ ]; k, {n, 0, 75} ]

%t Join[{4,0},With[{c=Table[{n,IntegerDigits[8^n]},{n,50}]},Table[ SelectFirst[ c,SequenceCount[ #[[2]],IntegerDigits[k]]>0&],{k,2,80}]][[All,1]]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Apr 13 2019 *)

%Y Cf. A030000, A063571, A176768.

%K base,nonn

%O 0,1

%A _Robert G. Wilson v_, Jun 24 2001