Numbers not a multiple of 6 whose reciprocals have a palindromic repeating part in base 6.
5, 10, 15, 45, 344, 2997, 3483, 10449
1
Is this sequence complete?
T. D. Noe, Plot of 8 terms
Wikipedia, Repeating decimal
(Mma) Select[Range[12000], (r = RealDigits[1/#, 6]; Mod[#, 6] > 0 && ! IntegerQ[r[[1,1]]] && r[[1,1]] == Reverse[r[[1,1]]]) &]
nonn,base
T. D. Noe, Jun 03 2016