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

1,2

Links

Table of n, a(n) for n=1..58.

Prog

(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

Crossrefs

Cf. A121805, A366487, A367359.

Sequence in context: A280241 A031121 A080655 * A354816 A199120 A118083

Adjacent sequences: A367355 A367356 A367357 * A367359 A367360 A367361

Keyword

nonn,base,fini,full

Author

N. J. A. Sloane, Nov 21 2023

Extensions

More terms from Michael S. Branicky, Nov 22 2023

Status

approved