A031956 - OEIS

%I #13 Aug 10 2021 14:19:47

%S 18,19,24,27,28,30,33,35,36,39,44,45,49,50,52,54,56,57,66,67,70,71,72,

%T 73,74,76,77,79,82,83,88,91,92,94,96,97,98,100,103,104,107,109,110,

%U 111,112,113,115,116,118,121,122,123,124,126,129

%N Numbers with exactly three distinct base-4 digits.

%Y Cf. A007090.

%K nonn,base

%O 1,1

%A _Clark Kimberling_