Palindromic numbers in bases 4 and 7 written in base 10.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =5a(5) =85a(6) =150a(7) =235a(8) =257a(9) =8802a(10) =9958a(11) =13655a(12) =14811a(13) =189806a(14) =428585a(15) =786435a(16) =9262450a(17) =31946605a(18) =34179458a(19) =387973685a(20) =424623193a(21) =430421657a(22) =640680742a(23) =742494286a(24) =1692399385a(25) =22182595205a(26) =30592589645