A043923 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, 132, 165, 177, 216, 226, 263, 275, 312, 324, 361, 373, 410, 422, 459, 475, 508, 520, 559, 569, 606, 618, 655, 667, 704, 716, 753, 765, 802, 818, 851, 863, 930, 949, 961, 998, 1010, 1047, 1059, 1096, 1108

Offset

1,1

Links

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

Mathematica

Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 7], {2, 4}]>0 || SequenceCount[IntegerDigits[n, 7], {4, 2}]>0, 1, 0], {n, 1200}], {1, 0}]][[1]] (* The program uses the SequencePosition and SequenceCount functions from Mathematica version 10 *) (* Harvey P. Dale, Mar 10 2016 *)

Crossrefs

Cf. A007093.

Sequence in context: A141115 A039320 A043143 * A160916 A091896 A101140

Adjacent sequences: A043920 A043921 A043922 * A043924 A043925 A043926

Keyword

nonn,base

Author

Clark Kimberling

Status

approved