A004285 Least positive multiple of n written in base 5 using only 0 and 1.

1, 11, 11, 1111, 10, 11, 1001, 10111, 1001, 110, 11111, 1111, 101, 1001, 110, 10111, 101111, 1001, 110111, 11110, 1001, 101011, 100101, 11111111, 100, 101, 11011, 11011, 1000011, 110, 111, 110101, 1011101, 111001, 10010, 11011, 101011, 111001, 1111, 101110, 10111

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Programs

Maple

N:= 100: # to get a(1) .. a(N)
S:= [[1,1]]:
A[1]:= 1:
Todo:= {$2..N}:
count:= 1:
for d from 2 while count < N do
  S:= map(t -> ([5*t[1],10*t[2]],[5*t[1]+1,10*t[2]+1]), S);
  for p in S do
    s:= p[1];
    Ts:= select(t -> s mod t = 0, Todo);
    Todo:= Todo minus Ts;
    count:= count + nops(Ts);
    for m in Ts do
         A[m]:= p[2];
    od
  od;
od:
seq(A[n],n=1..N); # Robert Israel, Dec 28 2015

PARI

a(n) = {k=1; while (vecmax(digits(k*n, 5)) != 1, k++); subst(Pol(digits(k*n, 5)), x, 10);} \\ Michel Marcus, Dec 27 2015

Extensions

a(33) corrected by Sean A. Irvine, Dec 26 2015

More terms from Michel Marcus, Dec 27 2015