Palindromes with exactly 2 prime factors (counted with multiplicity).

Terms

a(0) =4a(1) =6a(2) =9a(3) =22a(4) =33a(5) =55a(6) =77a(7) =111a(8) =121a(9) =141a(10) =161a(11) =202a(12) =262a(13) =303a(14) =323a(15) =393a(16) =454a(17) =505a(18) =515a(19) =535a(20) =545a(21) =565a(22) =626a(23) =707a(24) =717a(25) =737a(26) =767a(27) =818a(28) =838a(29) =878