%I
%S 5,12,55,308,510,2340,7286,9670,125406,222961,847169,639226,6250771,
%T 14929721
%N Least power of 3 having exactly n consecutive 4's in its decimal representation.
%C No more terms < 2*10^7.
%e a(3)=55 because 3^55(i.e. 174449211009120179071170507) is the smallest power of 3 to contain a run of 3 consecutive fours in its decimal form.
%t a = ""; Do[ a = StringJoin[a, "4"]; b = StringJoin[a, "4"]; k = 1; While[ StringPosition[ ToString[3^k], a] == {}  StringPosition[ ToString[3^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]
%K more,nonn,base
%O 1,1
%A _Shyam Sunder Gupta_, Aug 26 2007
%E a(11)a(14) from _Lars Blomberg_, Feb 02 2013
