A383246 Positive integers without the digit 0 such that every even digit except the rightmost is immediately followed by a smaller digit.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 91, 92, 93, 94, 95, 96, 97, 98, 99

Offset: 1

Author

Paolo Xausa, Apr 20 2025

Keywords

• nonn
• base
• easy

Comments

Conjecture: these are the terms of A342043, sorted.

Links

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

Crossrefs

Cf. A342043, A383245 (complement).

Cf. A377912, A382465, A382624, A382938, A383062, A383248, A383250, A383501.

Programs

Mathematica

A383246Q[k_] := FreeQ[#, 0] && FreeQ[Partition[#, 2, 1], {i_?EvenQ, j_} /; j >= i] &  [IntegerDigits[k]];
Select[Range[200], A383246Q]

Python

def ok(n):
    s = str(n)
    return "0" not in s and all(d not in "02468" or s[i]Michael S. Branicky, Apr 28 2025