A393015 Palindromic canyon numbers.

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, 21012, 31013, 32023, 32123, 41014, 42024, 42124, 43034

Offset

1,1

Comments

Canyon numbers (A134970) that are also palindromes (A002113).

All terms have an odd number of digits.

Finite because A134970 is finite, with largest term a(1013) = 9876543210123456789.

Links

Michael S. Branicky, Table of n, a(n) for n = 1..1013

Example

Illustration of 8720278 as a canyon palindrome:
  . . . . . . .
  8 . . . . . 8
  . 7 . . . 7 .
  . . . . . . .
  . . . . . . .
  . . . . . . .
  . . . . . . .
  . . 2 . 2 . .
  . . . . . . .
  . . . 0 . . .

Prog

(Python)
from itertools import chain, combinations as combs
downs = list(chain.from_iterable(combs("9876543210", r) for r in range(2, 11)))
afull = sorted(int("".join(D + D[-2::-1])) for D in downs)
print(afull[:53]) # Michael S. Branicky, Jan 31 2026

Crossrefs

Intersection of A002113 and A134970.

Cf. A134971, A173070.

Sequence in context: A162670 A252664 A134970 * A081365 A138131 A069858

Adjacent sequences: A393012 A393013 A393014 * A393016 A393017 A393018

Keyword

nonn,base,fini,full

Author

Alexander Yutkin, Jan 31 2026

Status

approved