A098953 Slowest increasing sequence where each number is such that at least one pair of adjacent digits are consecutive, the first of the pair being the smaller.

12, 23, 34, 45, 56, 67, 78, 89, 101, 112, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 134, 145, 156, 167, 178, 189, 201, 212, 223, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 245, 256, 267, 278, 289, 301, 312, 323, 334, 340, 341, 342, 343, 344, 345

Offset: 1

Author

Eric Angelini, Oct 21 2004

Keywords

• base
• easy
• nonn

Comments

Corrected by Zak Seidov, Apr 15 2007

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..10000

Crossrefs

A similar sequence: A082927

Programs

Python

from itertools import count, islice
def cond(n):
    d = list(map(int, str(n)))
    return any(d[i+1] == d[i]+1 for i in range(len(d)-1))
def agen():
    yield from filter(cond, count(1))
print(list(islice(agen(), 54))) # Michael S. Branicky, Dec 23 2021

Extensions

a(51) and beyond from Michael S. Branicky, Dec 23 2021