Triangular numbers that are palindromes in base 7.

Terms

a(0) =0a(1) =1a(2) =3a(3) =6a(4) =78a(5) =171a(6) =300a(7) =2850a(8) =8256a(9) =9453a(10) =14706a(11) =120786a(12) =208335a(13) =399171a(14) =405450a(15) =416328a(16) =448878a(17) =720600a(18) =5877306a(19) =6046503a(20) =6835753a(21) =9350650a(22) =10122750a(23) =18431556a(24) =19130205a(25) =22596003a(26) =35309406a(27) =499169406a(28) =934394835a(29) =969430528