Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most four elements.

A276720

Number of set partitions of [n] such that for each block b the smallest integer interval containing b has at most four elements.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =15a(5) =37a(6) =87a(7) =208a(8) =515a(9) =1271a(10) =3112a(11) =7594a(12) =18578a(13) =45510a(14) =111464a(15) =272839a(16) =667809a(17) =1634784a(18) =4002217a(19) =9797781a(20) =23985131a(21) =58715973a(22) =143739040a(23) =351879841a(24) =861416293a(25) =2108779100a(26) =5162371032a(27) =12637686756a(28) =30937555540a(29) =75736343956

External references