[[23]] is prime.

Primes up to 23: 2, 3, 5, 7, 11, 13, 17, 19, 23.

hex(1) is 1.

hex(2) is 7.

hex(3) is 19.

hex(4) is 37.

hex(5) is 61.

hex(6) is 91.

hex(7) is 127.

hex(8) is 169.

hex(9) is 217.

hex(10) is 271.

hex(11) is 331.

hex(12) is 397.

hex(13) is 469.

hex(14) is 547.

hex(15) is 631.

hex(16) is 721.

hex(17) is 817.

hex(18) is 919.

hex(19) is 1027.

hex(20) is 1141.

hex(21) is 1261.

hex(22) is 1387.

hex(23) is 1519.

… [Execution timed out]