Base 8 variant of A113846.
Similar arguments as for A113846 can be used to show that for all terms the first (and last) digit in base 8 is either 3 or 5.
All terms so far seem to follow one of the following patterns in base 8:
3w3, where w is an odd-length word consisting of the digits 2 and 5 only or of the digits 1, 4, 7 only.
abwba, where a is either 3 or 5, b is either the empty word or a single digit from 0 to 7 and w is an odd-length word consisting of the digits 0, 3, 6 only or of the digits 1, 4, 7 only.
By searching only through these patterns, much larger terms were found such as 473953150492647002336509521341 = 576666333366030333030663333666675_3.