Number of induced cycles in the 4 X n grid graph.

Terms

a(0) =0a(1) =3a(2) =9a(3) =24a(4) =58a(5) =125a(6) =251a(7) =490a(8) =948a(9) =1823a(10) =3485a(11) =6636a(12) =12614a(13) =23961a(14) =45495a(15) =86350a(16) =163856a(17) =310899a(18) =589873a(19) =1119144a(20) =2123266a(21) =4028261a(22) =7642379a(23) =14499018a(24) =27507300a(25) =52186343a(26) =99006909a(27) =187833924a(28) =356354718a(29) =676068905