Palindromes of the form 4n + 1 where n is also a palindrome. Palindromes arising in A083831.

Terms

a(0) =5a(1) =9a(2) =33a(3) =353a(4) =525a(5) =565a(6) =929a(7) =969a(8) =3553a(9) =35553a(10) =52125a(11) =52525a(12) =52925a(13) =56165a(14) =56565a(15) =56965a(16) =92129a(17) =92529a(18) =92929a(19) =96169a(20) =96569a(21) =96969a(22) =355553a(23) =3555553a(24) =5212125a(25) =5216125a(26) =5252525a(27) =5256525a(28) =5292925a(29) =5296925