A043164 Numbers k such that 1 and 7 occur juxtaposed in the base-8 representation of k but not of k-1.

15, 57, 79, 120, 143, 185, 207, 249, 271, 313, 335, 377, 399, 441, 456, 505, 527, 569, 591, 632, 655, 697, 719, 761, 783, 825, 847, 889, 911, 953, 960, 1039, 1081, 1103, 1144, 1167, 1209, 1231, 1273, 1295, 1337, 1359, 1401, 1423, 1465, 1480, 1529, 1551, 1593, 1615, 1656, 1679

Offset

1,1

Links

Table of n, a(n) for n=1..52.

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 8], {1, 7}]>0 || SequenceCount[IntegerDigits[n, 8], {7, 1}]>0, 1, 0], {n, 1500}], {0, 1}][[All, 2]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 26 2020 *)

Crossrefs

Cf. A007094.

Sequence in context: A184231 A389979 A039341 * A043944 A140379 A020222

Adjacent sequences: A043161 A043162 A043163 * A043165 A043166 A043167

Keyword

nonn,base

Author

Clark Kimberling

Extensions

a(44)-a(52) from Stefano Spezia, Feb 03 2026

Status

approved