A347298 Numbers that contain an even digit d immediately followed by a digit <= d.

20, 21, 22, 40, 41, 42, 43, 44, 60, 61, 62, 63, 64, 65, 66, 80, 81, 82, 83, 84, 85, 86, 87, 88, 100, 120, 121, 122, 140, 141, 142, 143, 144, 160, 161, 162, 163, 164, 165, 166, 180, 181, 182, 183, 184, 185, 186, 187, 188, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215

Offset: 1

Author

N. J. A. Sloane, Aug 26 2021

Keywords

• nonn
• base

Comments

Conjecture: This is precisely the list of numbers missing from A342042.

The conjecture is correct, see A342042 for details. - Sebastian Karlsson, Oct 02 2021

Links

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

Crossrefs

Cf. A342042, A377912 (complement).

Programs

Mathematica

A347298Q[k_] := MemberQ[Partition[IntegerDigits[k], 2, 1], {i_?EvenQ, j_} /; j <= i];
Select[Range[300], A347298Q] (* Paolo Xausa, Mar 17 2025 *)

Python

def ok(n):
    s = str(n)
    return any(s[i] in "2468" and s[i+1] <= s[i] for i in range(len(s)-1))
print([k for k in range(216) if ok(k)]) # Michael S. Branicky, Nov 28 2024