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-5 is member of a block >= b-1.

A287668

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-5 is member of a block >= b-1.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =15a(5) =52a(6) =203a(7) =877a(8) =4139a(9) =21107a(10) =115301a(11) =670059a(12) =4119316a(13) =26665103a(14) =181031235a(15) =1284643851a(16) =9500643629a(17) =73037739470a(18) =582346938182

External references