259041157538domain: NAppears in sequencesa(n) = 2*a(n-1) + 5*a(n-2) + 2*a(n-3).at n=21A101604Number of n X 2 0..2 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 3, and upper left element zero.at n=22A230269