reviewed
approved
proposed
editing
(Python)
from itertools import count
from sympy.ntheory.factor_ import digits
def A016026(n): return next(b for b in count(2) if (s := digits(n, b)[1:])[:(t:=len(s)+1>>1)]==s[:-t-1:-1]) # Chai Wah Wu, Jan 17 2024
Vincenzo Librandi and Hieronymus Fischer, <a href="/A016026/b016026.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 from Vincenzo Librandi).
A016026a(A016038(n)) = A016038(n) - 1, for n > 3.
A016026a(A006995(n)) = 2, for n > 1.
A016026a(A002113(n)) <= 10 for n > 1. (End)
