Number of arrangements of n+1 numbers x(i) in -1..1 with the sum of x(i)*x(i+1) equal to zero.

A188350

Number of arrangements of n+1 numbers x(i) in -1..1 with the sum of x(i)*x(i+1) equal to zero.

Terms

    a(0) =5a(1) =15a(2) =29a(3) =91a(4) =197a(5) =627a(6) =1477a(7) =4671a(8) =11693a(9) =36487a(10) =95405a(11) =293695a(12) =792525a(13) =2412175a(14) =6660989a(15) =20097243a(16) =56450693a(17) =169229571a(18) =481426405a(19) =1436666475a(20) =4126292293a(21) =12275100443a(22) =35511918037a(23) =105423983379a(24) =306684489749a(25) =909271908483

External references