Palindromic pentagonal numbers.

Terms

a(0) =0a(1) =1a(2) =5a(3) =22a(4) =1001a(5) =2882a(6) =15251a(7) =720027a(8) =7081807a(9) =7451547a(10) =26811862a(11) =54177145a(12) =1050660501a(13) =1085885801a(14) =1528888251a(15) =2911771192