Number of pairs of partitions (A<=B, that is, A is a refinement of B) of [n] such that A is noncrossing and its nontrivial blocks are of type {a,b} with a <= n and b > n.
A358397
Number of pairs of partitions (A<=B, that is, A is a refinement of B) of [n] such that A is noncrossing and its nontrivial blocks are of type {a,b} with a <= n and b > n.
Terms
- a(0) =1a(1) =1a(2) =3a(3) =9a(4) =37a(5) =157a(6) =811a(7) =4309a(8) =26327a(9) =164947a(10) =1151477a(11) =8224863a(12) =64158567a(13) =511177515a(14) =4386520201a(15) =38389960685a(16) =358214414675
External references
- oeis: A358397