A043595 - OEIS

%I #9 Apr 25 2021 01:26:18

%S 68,70,71,72,73,75,76,77,78,97,98,99,100,102,103,108,109,110,113,114,

%T 115,116,118,119,120,121,123,132,134,135,136,137,139,140,141,142,145,

%U 146,147,152,153,155,156,157,158,177,178,179

%N Numbers whose base-4 representation has exactly 4 runs.

%Y Cf. A007090.

%K nonn,base

%O 1,1

%A _Clark Kimberling_