T(n, k) is the number of order-preserving partial transformations (of an n-element chain) of height k (height(alpha) = |Im(alpha)|); triangle T read by rows.

A144066

T(n, k) is the number of order-preserving partial transformations (of an n-element chain) of height k (height(alpha) = |Im(alpha)|); triangle T read by rows.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =6a(5) =1a(6) =1a(7) =21a(8) =15a(9) =1a(10) =1a(11) =60a(12) =102a(13) =28a(14) =1a(15) =1a(16) =155a(17) =490a(18) =310a(19) =45a(20) =1a(21) =1a(22) =378a(23) =1935a(24) =2220a(25) =735a(26) =66a(27) =1a(28) =1a(29) =889

External references