A043199 Numbers k such that 2 and 7 occur juxtaposed in the base-9 representation of k but not of k-1.

25, 65, 106, 146, 187, 225, 268, 308, 349, 389, 430, 470, 511, 551, 585, 632, 673, 713, 754, 794, 835, 875, 916, 954, 997, 1037, 1078, 1118, 1159, 1199, 1240, 1280, 1314, 1361, 1402, 1442, 1483, 1523, 1564, 1604, 1645, 1683

Offset

1,1

Links

Table of n, a(n) for n=1..42.

Mathematica

Transpose[SequencePosition[Table[If[SequenceCount[IntegerDigits[n, 9], {2, 7}]>0||SequenceCount[IntegerDigits[n, 9], {7, 2}]>0, 1, 0], {n, 1700}], {0, 1}]][[2]] (* The program uses the SequenceCount and SequencePosition functions from Mathematica version 10 *) (* Harvey P. Dale, Jun 13 2016 *)

Crossrefs

Cf. A007095.

Sequence in context: A050993 A121387 A039376 * A043979 A033682 A020283

Adjacent sequences: A043196 A043197 A043198 * A043200 A043201 A043202

Keyword

nonn,base

Author

Clark Kimberling

Status

approved