A379903 Local minima in A342042, in order of appearance: numbers m such that A342042(k-1) > A342042(k) = m < A342042(k+1), for k >= 2.

0, 13, 15, 17, 19, 25, 27, 29, 35, 37, 39, 47, 49, 57, 59, 69, 79, 103, 105, 107, 109, 113, 304, 115, 117, 306, 119, 125, 506, 127, 129, 133, 135, 137, 508, 139, 147, 149, 153, 155, 157, 159, 169, 173, 175, 177, 179, 193, 195, 312, 197, 199, 233, 235, 237, 514

Offset: 1

Author

Paolo Xausa, Jan 05 2025

Keywords

• nonn
• base

Comments

a(1) = 0 is included as well.

Links

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

Crossrefs

Cf. A342042, A379901, A379902, A379904 (corresponding k's).

Programs

Python

from itertools import count, islice
def cond(s): return all(s[i+1] > s[i] for i in range(len(s)-1) if s[i] in "02468")
def A342042gen(): # generator of A342042
    seen, an = set(), 0
    while True:
        yield an
        seen.add(an)
        d = an%10
        an = minfirst = (1 - d%2)*(d+1)
        stran = str(an)
        while an in seen or not cond(stran):
            an += 1
            stran = str(an)
            if int(stran[0]) < minfirst:
                an = minfirst*10**(len(stran)-1)
def A3799034gen(): # generator of minima, indices
    g = A342042gen()
    p = float('inf'); m = next(g); n = next(g)
    for k in count(1):
        if p > m < n: yield (m, k)
        p, m, n = m, n, next(g)
print([t[0] for t in islice(A3799034gen(), 56)]) # Michael S. Branicky, Jan 08 2025