A063579 - OEIS

%I #6 Jun 26 2018 19:19:15

%S 2,1,9,11,32,53,64,75,82,69,91,134,144,161,189,133,132,198,192,253,

%T 225,219,268,236,284,252,255,374,296,315,355,372,404,421,414,450,361,

%U 538,501,471,459,482,533,544,445,666,640,586,615,565,665

%N Smallest k such that 4^k has exactly n 4's in its decimal representation.

%t a = {}; Do[k = 1; While[ Count[ IntegerDigits[4^k], 4] != n, k++ ]; a = Append[a, k], {n, 0, 50} ]; a

%K base,nonn

%O 0,1

%A _Robert G. Wilson v_, Aug 10 2001

%E Name corrected by _Jon E. Schoenfield_, Jun 26 2018