Number of non-equivalent (mod D_4) binary n X n matrices with 4 pairwise nonadjacent 1's.

Terms

a(0) =0a(1) =3a(2) =62a(3) =683a(4) =4015a(5) =16989a(6) =56196a(7) =158271a(8) =391917a(9) =882683a(10) =1836106a(11) =3587103a(12) =6638267a(13) =11747613a(14) =19985680a(15) =32879339a(16) =52490521a(17) =81638211a(18) =124000342a(19) =184440963a(20) =269135111a(21) =386033453a(22) =545007772a(23) =758491143a(24) =1041639045a(25) =1413189339a(26) =1895630946a(27) =2516334551a(28) =3307717267