A043137 Numbers k such that 1 and 2 occur juxtaposed in the base-7 representation of k but not of k-1.

9, 15, 58, 63, 105, 113, 156, 162, 205, 211, 254, 260, 303, 309, 352, 358, 401, 406, 441, 499, 505, 548, 554, 597, 603, 646, 652, 695, 701, 735, 791, 799, 842, 848, 891, 897, 940, 946, 989, 995, 1038, 1044, 1087, 1092, 1134, 1142

Offset

1,1

Links

Table of n, a(n) for n=1..46.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 7], {1, 2}]>0 || SequenceCount[IntegerDigits[n, 7], {2, 1}]>0, 1, 0], {n, 1200}], {0, 1}][[All, 2]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 11 2020 *)

Crossrefs

Cf. A007093.

Sequence in context: A146584 A276414 A175033 * A043917 A351499 A037378

Adjacent sequences: A043134 A043135 A043136 * A043138 A043139 A043140

Keyword

nonn,base

Author

Clark Kimberling

Status

approved