Number of -2..2 arrays x(0..n-1) of n elements with zero sum, and adjacent elements not both strictly positive and not both strictly negative.

A199892

Number of -2..2 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) =5a(2) =15a(3) =49a(4) =159a(5) =533a(6) =1783a(7) =6027a(8) =20437a(9) =69665a(10) =238191a(11) =817083a(12) =2809845a(13) =9685397a(14) =33450675a(15) =115736335a(16) =401065951a(17) =1391807783a(18) =4836111471a(19) =16823523661a(20) =58586196339a(21) =204217367081a(22) =712482836479

External references