A043143 Numbers k such that 2 and 4 occur juxtaposed in the base-7 representation of k but not of k-1.

18, 30, 67, 79, 116, 126, 165, 177, 210, 226, 263, 275, 312, 324, 361, 373, 410, 422, 459, 469, 508, 520, 553, 569, 606, 618, 655, 667, 704, 716, 753, 765, 802, 812, 851, 863, 882, 949, 961, 998, 1010, 1047, 1059, 1096, 1108

Offset

1,1

Links

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

Mathematica

SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 7], {2, 4}]>0 || SequenceCount[IntegerDigits[n, 7], {4, 2}]>0, 1, 0], {n, 1200}], {0, 1}] [[All, 2]] (* Harvey P. Dale, Mar 14 2022 *)

Crossrefs

Cf. A007093.

Sequence in context: A377185 A373844 A039320 * A043923 A160916 A091896

Adjacent sequences: A043140 A043141 A043142 * A043144 A043145 A043146

Keyword

nonn,base

Author

Clark Kimberling

Status

approved