Numbers n for which there are exactly four k such that n = k + reverse(k).

Terms

a(0) =44a(1) =165a(2) =404a(3) =424a(4) =444a(5) =464a(6) =484a(7) =504a(8) =524a(9) =544a(10) =564a(11) =584a(12) =1331a(13) =1515a(14) =1535a(15) =1555a(16) =1575a(17) =1595a(18) =1615a(19) =1635a(20) =1655a(21) =1675a(22) =1695a(23) =2112a(24) =2651a(25) =3872a(26) =4004a(27) =5984a(28) =13031a(29) =13231