A336827 a(n) is the largest integer that can be written in two bases smaller than n as mutually-reversed strings of digit(s), for n>=4.
1, 22, 22, 9831, 314767045, 1916060910, 455075911977
Offset: 4
Examples
a(5) is 22 because 22 = 211 (base 3) = 112 (base 4) is the largest such integer with both bases < 5 (here 3 and 4). a(6) is also 22 because there are no larger such integers with both bases < 6. a(7) is 9831 because 9831 = 303311 (base 5) and 113303 (base 6) is the largest such integer with both bases < 7 (here 5 and 6).
Extensions
a(9)-a(10) from Bert Dobbelaere, Sep 20 2020