Number of ordered set partitions of {1,2,...,n} such that no part has the same size as any of its three immediate predecessors.

A272431

Number of ordered set partitions of {1,2,...,n} such that no part has the same size as any of its three immediate predecessors.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =7a(4) =9a(5) =31a(6) =403a(7) =757a(8) =2873a(9) =12607a(10) =333051a(11) =1592977a(12) =10684875a(13) =105031681a(14) =697538325a(15) =8987362027a(16) =114294624633a(17) =975751249951

External references