n(5n-3)/2 is a palindromic heptagonal number.

Terms

a(0) =1a(1) =2a(2) =5a(3) =16a(4) =38a(5) =44a(6) =156a(7) =583a(8) =1359a(9) =1470a(10) =1556a(11) =53537a(12) =158476a(13) =161656a(14) =171657a(15) =190914a(16) =371778a(17) =382173a(18) =615769a(19) =1207698a(20) =1686537a(21) =16943262a(22) =88274141a(23) =496329416a(24) =765609041a(25) =1820198063a(26) =2497949426a(27) =2850685772a(28) =15911875336