Palindromes with exactly 4 palindromic prime factors (counted with multiplicity).

Terms

a(0) =88a(1) =484a(2) =525a(3) =686a(4) =808a(5) =2662a(6) =3773a(7) =3993a(8) =4444a(9) =6666a(10) =9999a(11) =14641a(12) =24442a(13) =34643a(14) =36663a(15) =40804a(16) =52525a(17) =134431a(18) =224422a(19) =336633a(20) =1234321a(21) =1596951a(22) =2060602a(23) =3090903a(24) =11333311a(25) =14699641a(26) =22888822a(27) =66888866a(28) =104060401a(29) =125888521