A062520 3^a(n) is smallest nonnegative power of 3 containing n.

10, 0, 3, 1, 5, 8, 8, 3, 4, 2, 21, 19, 17, 22, 11, 13, 17, 11, 7, 9, 18, 7, 19, 13, 5, 26, 19, 3, 24, 6, 16, 12, 13, 31, 15, 21, 24, 29, 18, 31, 17, 12, 18, 5, 12, 28, 16, 11, 15, 10, 35, 32, 33, 12, 26, 27, 8, 40, 26, 10, 21, 8, 19, 17, 24, 8, 33, 16, 9, 14, 35, 11, 6, 29, 18, 47

Offset

0,1

Links

Robert Israel, Table of n, a(n) for n = 0..9999

Example

a(1) = 0 since 3^0 = 1. a(2) = a(7) = a(27) = 3 because 3^3 = 27.

Maple

N:= 99:
count:= 1: A["0"]:= 10:
for n from 0 while count <= N do
  S:= convert(3^n, string); nS:= length(S);
  for m from 1 to 2 while count <= N do
    for i from 1 to nS+1-m while count <= N do
      if S[i] <> "0" and not assigned(A[S[i..i+m-1]]) then
         count:= count+1; A[S[i..i+m-1]]:= n;
      fi
    od
  od
od:
seq(A[convert(n, string)], n=0..N); # Robert Israel, Jun 14 2018

Mathematica

Table[k = 0; While[ StringPosition[ ToString[3^k], ToString[n] ] == {}, k++ ]; k, {n, 0, 75} ]

Prog

(Python)
def a(n):
    s, k = str(n), 0
    while s not in str(3**k): k += 1
    return k
print([a(n) for n in range(76)]) # Michael S. Branicky, Oct 04 2021

Crossrefs

Cf. A030000. Essentially the same as A063566. Cf. A000244.

Sequence in context: A291451 A323836 A365893 * A157962 A063741 A320227

Adjacent sequences: A062517 A062518 A062519 * A062521 A062522 A062523

Keyword

base,nonn

Author

Robert G. Wilson v, Jun 24 2001

Status

approved