Number of -2..2 arrays x(0..n+2) of n+3 elements with zero sum and no two or three adjacent elements summing to zero.

A200424

Number of -2..2 arrays x(0..n+2) of n+3 elements with zero sum and no two or three adjacent elements summing to zero.

Terms

    a(0) =20a(1) =80a(2) =212a(3) =594a(4) =1928a(5) =6780a(6) =23674a(7) =80750a(8) =271000a(9) =909282a(10) =3082640a(11) =10545846a(12) =36174576a(13) =123964062a(14) =424595930a(15) =1456168762a(16) =5004245744a(17) =17226485764a(18) =59361633214a(19) =204702938074a(20) =706403203606

External references