Triangle read by rows: T(n,k) = number of partial idempotent mappings (of an n-chain) with (right) waist exactly k.

A258579

Triangle read by rows: T(n,k) = number of partial idempotent mappings (of an n-chain) with (right) waist exactly k.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =1a(7) =4a(8) =7a(9) =11a(10) =1a(11) =8a(12) =17a(13) =30a(14) =48a(15) =1a(16) =16a(17) =43a(18) =86a(19) =150a(20) =241a(21) =1a(22) =32a(23) =113a(24) =258a(25) =492a(26) =846a(27) =1358a(28) =1a(29) =64

External references