Number of arrays of -2..2 integers x(1..n) with every x(i) in a subsequence of length 1, 2 or 3 with sum zero.

A193696

Number of arrays of -2..2 integers x(1..n) with every x(i) in a subsequence of length 1, 2 or 3 with sum zero.

Terms

    a(0) =1a(1) =5a(2) =23a(3) =83a(4) =299a(5) =1081a(6) =3931a(7) =14293a(8) =51955a(9) =188859a(10) =686519a(11) =2495537a(12) =9071325a(13) =32974351a(14) =119862177a(15) =435700975a(16) =1583780905a(17) =5757072535a(18) =20927062737a(19) =76070247573a(20) =276516705575

External references