Noncomposite reverse concatenations of divisors of n, sorted by n.

Terms

a(0) =1a(1) =31a(2) =421a(3) =71a(4) =131a(5) =191a(6) =2551a(7) =311a(8) =391331a(9) =431a(11) =911371a(12) =971a(13) =1031a(14) =1091a(15) =1173913931a(16) =1511a(17) =1571a(18) =1811a(19) =1931a(20) =2111a(21) =2411a(22) =24412261421a(23) =24719131a(24) =2711a(25) =289171a(26) =29214673421a(27) =3014371a(28) =30910331a(29) =32565251351a(30) =3371