A383248 Nonnegative integers without the digit 9 such that every odd digit except the rightmost is immediately followed by a larger digit.

0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 120, 121, 122, 123, 124, 125, 126, 127, 128

Offset: 1

Author

Paolo Xausa, Apr 25 2025

Keywords

• nonn
• base
• easy

Comments

Conjecture: these are the terms of A342044, sorted.

Links

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

Crossrefs

Cf. A342044, A383247 (complement).

Cf. A377912, A382465, A382624, A382938, A383062, A383246, A383250.

Programs

Mathematica

A383248Q[k_] := FreeQ[#, 9] && FreeQ[Partition[#, 2, 1], {i_?OddQ, j_} /; j <= i] & [IntegerDigits[k]];
Select[Range[0, 200], A383248Q]

Python

def ok(n):
    s = str(n)
    return "9" not in s and all(d not in "13579" or s[i]>d for i, d in enumerate(s, 1) if i < len(s))
print([k for k in range(129) if ok(k)]) # Michael S. Branicky, Apr 28 2025