132653domain: NAppears in sequencesExactly 6 digits from {1,2,3,4,5,6,7,8,9} can precede a(n) to form a prime.at n=8A032696Semiprimes of the form n^3 + 2.at n=23A259189Digits of composite k start as k', where k' is the arithmetic derivative of k.at n=4A375801