A043883 Numbers k such that 1 and 2 occur juxtaposed in the base-4 representation of k but not of k+1.

6, 9, 22, 27, 39, 41, 54, 57, 70, 73, 86, 91, 111, 118, 121, 134, 137, 159, 167, 169, 182, 185, 198, 201, 214, 219, 231, 233, 246, 249, 262, 265, 278, 283, 295, 297, 310, 313, 326, 329, 342, 347, 367, 374, 377, 447, 454, 457, 470

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Crossrefs

Cf. A007090.

Programs

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n,4],{1,2}]>0 || SequenceCount[IntegerDigits[n,4],{2,1}]>0,1,0],{n,500}],{1,0}][[All,1]] (* Harvey P. Dale, Aug 05 2021 *)