A372149 Palindrome numbers consisting only of odd digits.

1, 3, 5, 7, 9, 11, 33, 55, 77, 99, 111, 131, 151, 171, 191, 313, 333, 353, 373, 393, 515, 535, 555, 575, 595, 717, 737, 757, 777, 797, 919, 939, 959, 979, 999, 1111, 1331, 1551, 1771, 1991, 3113, 3333, 3553, 3773, 3993, 5115, 5335, 5555, 5775, 5995, 7117, 7337, 7557, 7777, 7997

Offset: 1

Author

James S. DeArmon, Apr 20 2024

Keywords

• nonn
• base

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..10000 (terms 1..1000 from James S. DeArmon)
• James S. DeArmon, Common LISP code to create A372149

Crossrefs

Intersection of A002113 and A014261.

Cf. A056524, A056525.

Programs

Mathematica

Select[Range[8000], PalindromeQ[#] && Times@@Boole[OddQ[IntegerDigits[#]]] == 1 &] (* Stefano Spezia, Apr 30 2024 *)

Python

from itertools import count, islice, product
def agen(): # generator of terms
    for d in count(1):
        for p in product("13579", repeat=d//2):
            left = "".join(p)
            for mid in [[""], "13579"][d&1]:
                yield int(left + mid + left[::-1])
print(list(islice(agen(), 60))) # Michael S. Branicky, Jun 01 2025

Extensions

Missing 1551 inserted by Stefano Spezia, Apr 30 2024