

A131544


Least power of 3 having exactly n consecutive 9's in its decimal representation.


10



2, 34, 35, 276, 1520, 2342, 8882, 32313, 164065, 265693, 1123487, 2421341, 6250773, 9995032, 68353789, 78927182
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OFFSET

1,1


COMMENTS



LINKS



EXAMPLE

a(3)=35 because 3^35 (i.e., 50031545098999707) is the smallest power of 3 to contain a run of 3 consecutive nines in its decimal form.


MATHEMATICA

a = ""; Do[ a = StringJoin[a, "9"]; b = StringJoin[a, "9"]; k = 1; While[ StringPosition[ ToString[3^k], a] == {}  StringPosition[ ToString[3^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]


PROG

(Python)
....m, s = 1, '9'*n
....for i in range(1, 10**9):
........m *= 3
........if s in str(m):
............return i
....return "search limit reached." # Chai Wah Wu, Dec 11 2014


CROSSREFS



KEYWORD

more,nonn,base


AUTHOR



EXTENSIONS



STATUS

approved



