%I #11 Apr 21 2021 04:23:51
%S 1,2,3,16,21,26,31,32,37,42,47,48,53,58,63,65,66,67,104,105,107,124,
%T 125,126,129,130,131,148,150,151,188,189,190,193,194,195,212,214,215,
%U 232,233,235,256,336,341,346,351,426,511,512,597
%N Numbers whose base-4 run lengths alternate: odd, even, odd, ...
%Y Cf. A007090.
%K nonn,base
%O 1,2
%A _Clark Kimberling_