A043931 Numbers k such that 5 and 6 occur juxtaposed in the base-7 representation of k but not of k+1.

41, 47, 90, 96, 139, 145, 188, 194, 237, 243, 293, 335, 341, 384, 390, 433, 439, 482, 488, 531, 537, 580, 586, 636, 678, 684, 727, 733, 776, 782, 825, 831, 874, 880, 923, 929, 979, 1021, 1027, 1070, 1076, 1119, 1125, 1168, 1174

Offset

1,1

Links

Table of n, a(n) for n=1..45.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 7], {5, 6}]>0 || SequenceCount[IntegerDigits[n, 7], {6, 5}]>0, 1, 0], {n, 1200}], {1, 0}][[All, 1]] (* Harvey P. Dale, Aug 05 2021 *)

Crossrefs

Cf. A007093.

Sequence in context: A186280 A039328 A043151 * A139219 A185658 A074485

Adjacent sequences: A043928 A043929 A043930 * A043932 A043933 A043934

Keyword

nonn,base

Author

Clark Kimberling

Status

approved