A031949 Numbers with exactly two distinct base-4 digits.

4, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 20, 22, 23, 25, 26, 29, 31, 32, 34, 37, 38, 40, 41, 43, 46, 47, 48, 51, 53, 55, 58, 59, 60, 61, 62, 64, 65, 68, 69, 80, 81, 84, 86, 87, 89, 90, 93, 95, 101, 102, 105, 106, 117, 119, 125, 127, 128, 130

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Crossrefs

Cf. A007090.

Programs

Mathematica

db4Q[n_]:=Count[DigitCount[n,4],?(#>0&)]==2; Select[Range[200],db4Q] (* _Harvey P. Dale, Jan 13 2019 *)