A044270 Numbers k such that string 2,1 occurs in the base 9 representation of k but not of k-1.

19, 100, 171, 181, 262, 343, 424, 505, 586, 667, 748, 829, 900, 910, 991, 1072, 1153, 1234, 1315, 1396, 1477, 1539, 1629, 1639, 1720, 1801, 1882, 1963, 2044, 2125, 2206, 2287, 2358, 2368, 2449, 2530, 2611, 2692, 2773, 2854

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Mathematica

A044270Q[k_] := StringContainsQ[IntegerString[k, 9], "21"] && StringFreeQ[IntegerString[k - 1, 9], "21"];
Select[Range[5000], A044270Q] (* Paolo Xausa, Sep 02 2025 *)

Crossrefs

Sequence in context: A129701 A221746 A241236 * A044651 A287303 A142216

Adjacent sequences: A044267 A044268 A044269 * A044271 A044272 A044273

Keyword

nonn,base

Author

Clark Kimberling

Status

approved