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A062525 8^a(n) is smallest power of 8 containing the string 'n'.

%I A062525 #8 Dec 25 2019 23:11:41
%S A062525 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 A062525 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 A062525 13,16,25,11,11,20,25,6,27,2,14,24,8,5,20,23,7,8,10,10,13
%N A062525 8^a(n) is smallest power of 8 containing the string 'n'.
%H A062525 Robert Israel, <a href="/A062525/b062525.txt">Table of n, a(n) for n = 0..9999</a>
%p A062525 F:= proc(dmax) local R,count,x,N,L,d,i,v, p;
%p A062525 count:= 0: x:= 1/8: N:= 10^dmax:
%p A062525 for p from 0 while count < N do
%p A062525   x:= 8*x;
%p A062525   L:= convert(x,base,10);
%p A062525   for d from 1 to min(dmax, nops(L)) do
%p A062525     for i from 1 to nops(L)-d+1 do
%p A062525       v:= add(L[j]*10^(j-i),j=i..i+d-1);
%p A062525       if not assigned(R[v]) then count:= count+1; R[v]:= p fi
%p A062525 od od od;
%p A062525 seq(R[v],v=0..N-1);
%p A062525 end proc:
%p A062525 F(2); # _Robert Israel_, Dec 25 2019
%t A062525 Table[k = 0; While[ StringPosition[ ToString[8^k], ToString[n] ] == {}, k++ ]; k, {n, 0, 75} ]
%t A062525 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 A062525 Cf. A030000, A063571, A176768.
%K A062525 base,nonn
%O A062525 0,1
%A A062525 _Robert G. Wilson v_, Jun 24 2001