Number of -2..2 arrays x(i) of n+1 elements i=1..n+1 with x(i)+x(j), x(i+1)+x(j+1), -(x(i)+x(j+1)), and -(x(i+1)+x(j)) having one or three distinct values for every i<=n and j<=n.

A211460

Number of -2..2 arrays x(i) of n+1 elements i=1..n+1 with x(i)+x(j), x(i+1)+x(j+1), -(x(i)+x(j+1)), and -(x(i+1)+x(j)) having one or three distinct values for every i<=n and j<=n.

Terms

    a(0) =21a(1) =53a(2) =121a(3) =259a(4) =549a(5) =1119a(6) =2285a(7) =4575a(8) =9185a(9) =18275a(10) =36437a(11) =72387a(12) =144013a(13) =286211a(14) =569361a(15) =1132703a(16) =2254869a(17) =4490887a(18) =8948013a(19) =17838815a(20) =35573537a(21) =70976563a(22) =141639157a(23) =282775411a(24) =564615853a(25) =1127756979a(26) =2252749969a(27) =4501187503

External references