Number of set partitions of [n] such that j is member of block b only if b = 1 or at least one of j-1, ..., j-4 is member of a block >= b-1.
A287667
Number of set partitions of [n] such that j is member of block b only if b = 1 or at least one of j-1, ..., j-4 is member of a block >= b-1.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =5a(4) =15a(5) =52a(6) =203a(7) =876a(8) =4116a(9) =20827a(10) =112538a(11) =645045a(12) =3900512a(13) =24769152a(14) =164546915a(15) =1139818861a(16) =8209631792a(17) =61331709492a(18) =474221335902
External references
- oeis: A287667