Palindromes n such that 6n + 1 is also a palindrome.

Terms

a(0) =1a(1) =9a(2) =99a(3) =121a(4) =131a(5) =999a(6) =9999a(7) =12021a(8) =12121a(9) =13031a(10) =13131a(11) =99999a(12) =999999a(13) =1202021a(14) =1203021a(15) =1212121a(16) =1213121a(17) =1302031a(18) =1303031a(19) =1312131a(20) =1313131a(21) =9999999a(22) =99999999a(23) =120202021a(24) =120212021a(25) =120303021a(26) =120313021a(27) =121202121a(28) =121212121