Number of -7..7 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

A199897

Number of -7..7 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) =15a(2) =85a(3) =799a(4) =5839a(5) =51395a(6) =406575a(7) =3500269a(8) =28684325a(9) =245319361a(10) =2048301005a(11) =17499467353a(12) =147731409251

External references