Number of zero-sum nX1 -1..1 arrays with every element equal to at least one horizontal or vertical neighbor.

A201840

Number of zero-sum nX1 -1..1 arrays with every element equal to at least one horizontal or vertical neighbor.

Terms

    a(0) =0a(1) =1a(2) =1a(3) =3a(4) =1a(5) =9a(6) =7a(7) =25a(8) =25a(9) =83a(10) =85a(11) =277a(12) =327a(13) =965a(14) =1267a(15) =3479a(16) =4933a(17) =12713a(18) =19267a(19) =47079a(20) =75269a(21) =176317a(22) =294185a(23) =665893a(24) =1149735a(25) =2531711a(26) =4492395a(27) =9677791a(28) =17552673a(29) =37160277

External references