A043986 Numbers k such that 4 and 5 occur juxtaposed in the base-9 representation of k but not of k+1.

41, 49, 122, 130, 203, 211, 284, 292, 365, 377, 449, 454, 527, 535, 608, 616, 689, 697, 770, 778, 851, 859, 932, 940, 1013, 1021, 1094, 1106, 1178, 1183, 1256, 1264, 1337, 1345, 1418, 1426, 1499, 1507, 1580, 1588, 1661, 1669

Offset

1,1

Links

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

Mathematica

Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 9], {4, 5}]+SequenceCount[IntegerDigits[n, 9], {5, 4}]>0, 1, 0], {n, 1700}], {1, 0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* Harvey P. Dale, Oct 03 2015 *)

Crossrefs

Cf. A007095.

Sequence in context: A074485 A039383 A043206 * A124967 A224443 A349779

Adjacent sequences: A043983 A043984 A043985 * A043987 A043988 A043989

Keyword

nonn,base

Author

Clark Kimberling

Status

approved