A043213 Numbers k such that 6 and 7 occur juxtaposed in the base-9 representation of k but not of k-1.

61, 69, 142, 150, 223, 231, 304, 312, 385, 393, 466, 474, 547, 549, 621, 636, 709, 717, 790, 798, 871, 879, 952, 960, 1033, 1041, 1114, 1122, 1195, 1203, 1276, 1278, 1350, 1365, 1438, 1446, 1519, 1527, 1600, 1608, 1681, 1689

Offset

1,1

Links

Table of n, a(n) for n=1..42.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 9], {6, 7}]>0 || SequenceCount[IntegerDigits[n, 9], {7, 6}]>0, 1, 0], {n, 1700}], {0, 1}][[All, 2]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 27 2020 *)

Crossrefs

Cf. A007095.

Sequence in context: A045712 A090154 A039390 * A043993 A165287 A064229

Adjacent sequences: A043210 A043211 A043212 * A043214 A043215 A043216

Keyword

nonn,base

Author

Clark Kimberling

Status

approved