A379901 Local maxima in A342042, in order of appearance: numbers m such that A342042(k-1) < A342042(k) = m > A342042(k+1), for k >= 2.

30, 50, 70, 90, 51, 71, 91, 52, 72, 92, 73, 93, 74, 94, 95, 96, 301, 501, 701, 901, 303, 502, 503, 702, 902, 703, 505, 704, 705, 903, 307, 507, 707, 904, 905, 906, 907, 909, 509, 710, 910, 911, 309, 510, 711, 912, 311, 511, 712, 313, 913, 512, 513, 713, 914, 515

Offset: 1

Author

Paolo Xausa, Jan 05 2025

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A342042, A379902 (corresponding k's), A379903, A379904.

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 A3799012gen(): # generator of maxima, indices
    g = A342042gen()
    p = next(g)
    m = next(g)
    n = next(g)
    for k in count(2):
        if p < m > n: yield (m, k)
        p, m, n = m, n, next(g)
print([t[0] for t in islice(A3799012gen(), 56)]) # Michael S. Branicky, Jan 08 2025