4193821domain: NAppears in sequencesa(n) = 2^n - n^2 + 1.at n=22A030110a(n) = (45^n - 1)/44.at n=5A218748Number of n X 2 0..1 arrays with every element unequal to 0, 1, 3 or 4 king-move adjacent elements, with upper left element zero.at n=21A303802