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-7 is member of a block >= b-1.

A287670

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-7 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) =4140a(9) =21147a(10) =115974a(11) =678434a(12) =4209827a(13) =27578206a(14) =189954361a(15) =1370870811a(16) =10334533723a(17) =81166980407a(18) =662588540048

External references