2073991domain: NAppears in sequencesSemiprimes whose prime factors are distinct and the reversal of one factor is equal to the other.at n=23A083815Number of ways to place zero or more nonadjacent 0,0 1,0 2,0 3,0 4,0 polyhexes in any orientation on a planar nXnXn triangular grid.at n=9A155237