Number of binary relations R on [n] such that the (unique) idempotent in {R,R^2,R^3,...} is an equivalence relation.

A369397

Number of binary relations R on [n] such that the (unique) idempotent in {R,R^2,R^3,...} is an equivalence relation.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =157a(4) =26345a(5) =18218521a(6) =47136254765

External references