A083996 a(1) = 1; then numbers such that the concatenation a(n)a(n-1)...a(2)a(1)a(2)...a(n-1)a(n) is a prime for n>1.

1, 3, 9, 3, 11, 1, 23, 49, 21, 3, 17, 9, 13, 3, 47, 19, 41, 43, 3, 51, 371, 183, 3, 21, 103, 53, 33, 33, 91, 41, 99, 433, 443, 93, 111, 501, 73, 11, 139, 177, 171, 429, 521, 333, 417, 1, 341, 213, 253, 171, 387, 171, 779, 463, 687, 861, 1131, 39, 539, 231, 1513, 263, 369