Number of -4..4 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

A199894

Number of -4..4 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

Terms

    a(0) =1a(1) =9a(2) =37a(3) =209a(4) =1043a(5) =5725a(6) =30199a(7) =164993a(8) =890299a(9) =4877477a(10) =26632013a(11) =146499083a(12) =805700567a(13) =4449304857a(14) =24590147861a(15) =136249639279a(16) =755738351775

External references