Primes formed by concatenating palindromes having even number of digits with 1.

Terms

a(0) =331a(1) =661a(2) =881a(3) =991a(4) =12211a(5) =14411a(6) =15511a(7) =20021a(8) =21121a(9) =23321a(10) =24421a(11) =29921a(12) =33331a(13) =35531a(14) =41141a(15) =45541a(16) =47741a(17) =50051a(18) =51151a(19) =57751a(20) =59951a(21) =63361a(22) =71171a(23) =72271a(24) =74471a(25) =75571a(26) =81181a(27) =84481a(28) =99991a(29) =1022011