Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.

A221276

Number of 2 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.

Terms

    a(0) =0a(1) =4a(2) =4a(3) =25a(4) =52a(5) =196a(6) =520a(7) =1681a(8) =4840a(9) =14884a(10) =44044a(11) =133225a(12) =397852a(13) =1196836a(14) =3585040a(15) =10764961a(16) =32278480a(17) =96864964a(18) =290545684a(19) =871725625a(20) =2615029252a(21) =7845353476a(22) =23535617560a(23) =70607649841a(24) =211821620920a(25) =635467254244

External references