Number of palindromes (in base 3) below 3^n.

Terms

a(0) =0a(1) =2a(2) =4a(3) =10a(4) =16a(5) =34a(6) =52a(7) =106a(8) =160a(9) =322a(10) =484a(11) =970a(12) =1456a(13) =2914a(14) =4372a(15) =8746a(16) =13120a(17) =26242a(18) =39364a(19) =78730a(20) =118096a(21) =236194a(22) =354292a(23) =708586a(24) =1062880a(25) =2125762a(26) =3188644a(27) =6377290a(28) =9565936a(29) =19131874