A043947 Numbers k such that 2 and 5 occur juxtaposed in the base-8 representation of k but not of k+1.

21, 42, 85, 106, 149, 175, 213, 234, 277, 298, 343, 362, 405, 426, 469, 490, 533, 554, 597, 618, 661, 687, 725, 746, 789, 810, 855, 874, 917, 938, 981, 1002, 1045, 1066, 1109, 1130, 1173, 1199, 1237, 1258, 1301, 1322, 1407

Offset

1,1

Links

Table of n, a(n) for n=1..43.

Mathematica

Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 8], {2, 5}]>0||SequenceCount[IntegerDigits[n, 8], {5, 2}]>0, 1, 0], {n, 1500}], {1, 0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* Harvey P. Dale, Jul 19 2016 *)

Crossrefs

Cf. A007094.

Sequence in context: A175805 A039344 A043167 * A335477 A263877 A041870

Adjacent sequences: A043944 A043945 A043946 * A043948 A043949 A043950

Keyword

nonn,base

Author

Clark Kimberling

Status

approved