Number of arrays of -6..6 integers x(1..n) with every x(i) in a subsequence of length 1 or 2 with sum zero.

A193646

Number of arrays of -6..6 integers x(1..n) with every x(i) in a subsequence of length 1 or 2 with sum zero.

Terms

    a(0) =1a(1) =13a(2) =37a(3) =205a(4) =793a(5) =3673a(6) =15481a(7) =68485a(8) =295453a(9) =1291237a(10) =5605489a(11) =24418801a(12) =106183729a(13) =462160957a(14) =2010578005a(15) =8748949309a(16) =38065839625a(17) =165631750345a(18) =720670846249

External references