A367358 Indices k at which either the leading digit or the length of A121805(k) changes.

1, 2, 3, 4, 5, 7, 8, 11, 13, 17, 19, 21, 22, 24, 45, 69, 90, 107, 127, 145, 164, 185, 204, 422, 614, 822, 1007, 1174, 1392, 1585, 1757, 1943, 4115, 6039, 8123, 9974, 11641, 13814, 15738, 17822, 19673, 41413, 60643, 81477, 99995, 114281, 132138, 151369, 172201, 190720, 408111, 646206, 854539, 1039724, 1373058, 1551630, 1743937, 1952271

Offset: 1

Author

N. J. A. Sloane, Nov 21 2023

Keywords

• nonn
• base
• fini
• full

Crossrefs

Cf. A121805, A366487, A367359.

Programs

Python

def agen(): # generator of terms
    n, an, y, prev_lead, prev_length = 1, 1, 1, None, None
    while y < 10:
        san = str(an)
        lead, length = san[0], len(san)
        if lead != prev_lead or length != prev_length:
            yield n
        an, y = an + 10*(an%10), 1
        while y < 10:
            if str(an+y)[0] == str(y):
                an += y
                break
            y += 1
        n, prev_lead, prev_length = n+1, lead, length
print(list(agen())) # Michael S. Branicky, Nov 22 2023

Extensions

More terms from Michael S. Branicky, Nov 22 2023