Number of -3..3 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

A199893

Number of -3..3 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) =7a(2) =25a(3) =111a(4) =461a(5) =2035a(6) =8823a(7) =39053a(8) =172355a(9) =767425a(10) =3420017a(11) =15311495a(12) =68665323a(13) =308805403a(14) =1391091909a(15) =6278869703a(16) =28381760049a(17) =128482271031a(18) =582346682067

External references