Number of non-equivalent binary n X n matrices with three pairwise nonadjacent 1's.

Terms

a(0) =0a(1) =6a(2) =40a(3) =210a(4) =681a(5) =1919a(6) =4443a(7) =9481a(8) =18206a(9) =33164a(10) =56570a(11) =92996a(12) =146175a(13) =223565a(14) =330981a(15) =479779a(16) =678508a(17) =943586a(18) =1287036a(19) =1731654a(20) =2293765a(21) =3004011a(22) =3883935a(23) =4973645a(24) =6300906a(25) =7917064a(26) =9857198a(27) =12185816a(28) =14946491a(29) =18218969