255359

Appears in sequences

• Number of nonisomorphic Hamiltonian cycles on (4n-2) X (4n-2) square grid of points with four-fold rotational symmetry (and no other symmetry).at n=3A237432
• a(n) = 1 + 2 * (a(n-1) + a(n-4) + a(n-6)) + a(n-7) for n>3, with initial values 0 if n<0, and 1,3,8,18 for n=0..3.at n=15A317188