a(n) is the number of "generalized signotopes", i.e., mappings X:{{1..n} choose 3}->{+,-} such that for any four indices a < b < c < d, the sequence X(a,b,c), X(a,b,d), X(a,c,d), X(b,c,d) changes its sign at most twice (equivalently +-+- and -+-+ are forbidden).

A328377

a(n) is the number of "generalized signotopes", i.e., mappings X:{{1..n} choose 3}->{+,-} such that for any four indices a < b < c < d, the sequence X(a,b,c), X(a,b,d), X(a,c,d), X(b,c,d) changes its sign at most twice (equivalently +-+- and -+-+ are forbidden).