A044518 Numbers k such that the string 5,5 occurs in the base-6 representation of k but not of k+1.

35, 71, 107, 143, 179, 215, 251, 287, 323, 359, 395, 431, 467, 503, 539, 575, 611, 647, 683, 719, 755, 791, 827, 863, 899, 935, 971, 1007, 1043, 1079, 1115, 1151, 1187, 1223, 1295, 1331, 1367, 1403, 1439, 1475, 1511, 1547, 1583

Offset

1,1

Comments

A 6-automatic set: membership is determined by comparing the base-6 representation of the number to the regular expression /5?([^5]+5)*([^45]|[^5]4)55+/. - Charles R Greathouse IV, Feb 11 2012

1259 = 36*34 + 35 is the first number of the form 36*(m-1) + 35, for m >= 1, that is not in the sequence, because (1259)_6 = 5455 and (1260)_6 = 5500. See A350055 for {36*n + 35}. - Wolfdieter Lang, Feb 10 2022

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000 (first 500 terms from Vincenzo Librandi)

Index entries for 6-automatic sequences.

Mathematica

f[n_]:=Length[StringPosition[ToString[FromDigits[IntegerDigits[n, 6]]], "55", 1]]; Select[Table[n, {n, 2000}], f[#]>0&&f[#+1]==0&] (* Vincenzo Librandi, Feb 11 2012 *)
SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 6], {5, 5}]>0, 1, 0], {n, 2000}], {1, 0}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 13 2019 *)

Crossrefs

Cf. A350055.

Sequence in context: A031481 A044137 A350055 * A039382 A043205 A043985

Adjacent sequences: A044515 A044516 A044517 * A044519 A044520 A044521

Keyword

nonn,base,easy

Author

Clark Kimberling

Status

approved