A063596 - OEIS

A063596

Least k >= 0 such that 6^k has exactly n 0's in its decimal representation.

%I #13 Jun 19 2018 05:55:48

%S 0,10,9,13,19,43,56,41,94,79,113,100,88,112,124,127,138,176,144,175,

%T 174,168,170,210,245,228,182,237,287,260,312,321,294,347,389,365,401,

%U 386,390,419,460,425,438,426,488,490,520,458,489,521,513

%N Least k >= 0 such that 6^k has exactly n 0's in its decimal representation.

%t a = {}; Do[k = 0; While[ Count[ IntegerDigits[6^k], 0] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

%t With[{pwr6=Table[{n,DigitCount[6^n,10,0]},{n,1000}]},Join[{0},Transpose[ Table[ SelectFirst[pwr6,#[[2]]==i&],{i,60}]][[1]]]] (* _Harvey P. Dale_, Dec 15 2014 *)

%o (PARI) A063596(n)=for(k=0, oo, #select(d->!d, digits(6^k))==n&&return(k)) \\ _M. F. Hasler_, Jun 14 2018

%Y Cf. A031146 (analog for 2^k), A063555 (for 3^k), A063575 (for 4^k), A063585 (for 5^k), A063606 (for 7^k), A063616 (for 8^k), A063626 (for 9^k).

%K base,nonn

%O 0,2

%A _Robert G. Wilson v_, Aug 10 2001

%E a(0) changed to 0 (as in A031146, A063555, ...) and better title from _M. F. Hasler_, Jun 14 2018