A393807 Palindromes that have only one smallest digit (strict minimum).

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 101, 202, 212, 303, 313, 323, 404, 414, 424, 434, 505, 515, 525, 535, 545, 606, 616, 626, 636, 646, 656, 707, 717, 727, 737, 747, 757, 767, 808, 818, 828, 838, 848, 858, 868, 878, 909, 919, 929, 939, 949, 959, 969, 979, 989, 11011, 12021, 13031, 14041, 15051

Offset

1,3

Comments

All terms have an odd number of digits. The sequence is infinite.

Differs first from A266139 in not having 12121. - R. J. Mathar, Mar 06 2026

Links

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

Mathematica

Select[Range[0, 15200], PalindromeQ[#] &&Count[digits=IntegerDigits[#], Min[digits]]==1 &] (* Stefano Spezia, Feb 28 2026 *)

Prog

(Python)
from itertools import count, islice, product
def agen():
    yield from range(10)
    for digs in count(3, step=2):
        for first in "123456789":
            for left in product("123456789", repeat=(digs-3)//2):
                left = "".join(left)
                mn = int(min(first+left))
                for mid in "".join(map(str, range(0, mn))):
                    yield int(first + left + mid + left[::-1] + first)
print(list(islice(agen(), 60))) # Michael S. Branicky, Feb 28 2026

Crossrefs

Supersequence of A393015.

Cf. A002113, A110785, A134970.

Sequence in context: A207954 A193412 A266139 * A154562 A193409 A280823

Adjacent sequences: A393804 A393805 A393806 * A393809 A393810 A393811

Keyword

nonn,base

Author

Alexander Yutkin, Feb 28 2026

Status

approved