Both k and the reverse of k are pentagonal numbers (A000326).

Terms

a(0) =0a(1) =1a(2) =5a(3) =22a(4) =210a(5) =287a(6) =782a(7) =1001a(8) =2882a(9) =7740a(10) =15251a(11) =77180a(12) =565187a(13) =720027a(14) =781565a(15) =7081807a(16) =7451547a(17) =26811862a(18) =54177145a(19) =206489067a(20) =246214610a(21) =760984602a(22) =1050660501a(23) =1085885801a(24) =1528888251a(25) =2642326276a(26) =2911771192a(27) =6726232462a(28) =24375132126a(29) =62123157342