A043924 Numbers k such that 2 and 5 occur juxtaposed in the base-7 representation of k but not of k+1.

19, 37, 68, 86, 117, 139, 166, 184, 215, 233, 265, 282, 313, 331, 362, 380, 411, 429, 460, 482, 509, 527, 558, 576, 608, 625, 656, 674, 705, 723, 754, 772, 803, 825, 852, 870, 901, 919, 979, 999, 1017, 1048, 1066, 1097, 1115

Offset

1,1

Links

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

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 7], {2, 5}]>0 || SequenceCount[IntegerDigits[n, 7], {5, 2}]>0, 1, 0], {n, 1200}], {1, 0}] [[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 08 2020 *)

Crossrefs

Cf. A007093.

Sequence in context: A154944 A039321 A043144 * A301617 A211821 A061237

Adjacent sequences: A043921 A043922 A043923 * A043925 A043926 A043927

Keyword

nonn,base

Author

Clark Kimberling

Status

approved