A043991 Numbers k such that 5 and 7 occur juxtaposed in the base-9 representation of k but not of k+1.

52, 68, 133, 149, 214, 230, 295, 311, 376, 392, 457, 476, 538, 554, 620, 635, 700, 716, 781, 797, 862, 878, 943, 959, 1024, 1040, 1105, 1121, 1186, 1205, 1267, 1283, 1349, 1364, 1429, 1445, 1510, 1526, 1591, 1607, 1672, 1688

Offset

1,1

Links

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

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 9], {5, 7}]>0 || SequenceCount[ IntegerDigits[n, 9], {7, 5}]>0, 1, 0], {n, 2000}], {1, 0}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 23 2019 *)

Crossrefs

Cf. A007095.

Sequence in context: A107933 A039388 A043211 * A326235 A118148 A111173

Adjacent sequences: A043988 A043989 A043990 * A043992 A043993 A043994

Keyword

nonn,base

Author

Clark Kimberling

Status

approved