A043879 Numbers k such that 1 and 2 occur juxtaposed in the base-3 representation of k but not of k+1.

5, 7, 17, 23, 25, 32, 34, 53, 59, 61, 71, 77, 79, 86, 88, 98, 104, 106, 113, 115, 161, 167, 169, 179, 185, 187, 215, 221, 223, 233, 239, 241, 248, 250, 260, 266, 268, 275, 277, 296, 302, 304, 314, 320, 322, 329, 331, 341, 347, 349

Offset

1,1

Links

Table of n, a(n) for n=1..50.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 3], {1, 2}]>0 || SequenceCount[IntegerDigits[n, 3], {2, 1}]>0, 1, 0], {n, 400}], {1, 0}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 18 2018 *)

Crossrefs

Cf. A007089.

Sequence in context: A331895 A164120 A342799 * A370855 A044966 A359297

Adjacent sequences: A043876 A043877 A043878 * A043880 A043881 A043882

Keyword

nonn,base

Author

Clark Kimberling

Status

approved