Triangular numbers that are palindromes in base 3.

Terms

a(0) =0a(1) =1a(2) =10a(3) =28a(4) =91a(5) =820a(6) =7381a(7) =65341a(8) =66430a(9) =597871a(10) =1633528a(11) =5380840a(12) =48339028a(13) =48427561a(14) =139386556a(15) =435848050a(16) =1178284240a(17) =3529890253a(18) =3922632451a(19) =32614707700a(20) =35296517971a(21) =35303692060a(22) =101891588176a(23) =292358957446a(24) =295883935480a(25) =317733228541a(26) =859413596320