%I

%S 21,37,41,42,43,45,53,69,73,74,75,77,81,82,83,84,86,87,89,90,91,93,

%T 101,105,106,107,109,117,133,137,138,139,141,145,146,147,148,150,151,

%U 153,154,155,157,161,162,163,164,166,167,168,172

%N (1/2)(n-th number whose base 2 representation has exactly 6 runs).

%K nonn,base

%O 1,1

%A _Clark Kimberling_