Triangular array read by rows. T(n,k) is the number of labeled posets on [n] of rank at most one with exactly k elements of positive indegree, n >= 0, 0 <= k <= max{0,n-1}.
A369919
Triangular array read by rows. T(n,k) is the number of labeled posets on [n] of rank at most one with exactly k elements of positive indegree, n >= 0, 0 <= k <= max{0,n-1}.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =1a(5) =9a(6) =3a(7) =1a(8) =28a(9) =54a(10) =4a(11) =1a(12) =75a(13) =490a(14) =270a(15) =5a(16) =1a(17) =186a(18) =3375a(19) =6860a(20) =1215a(21) =6a(22) =1a(23) =441a(24) =20181a(25) =118125a(26) =84035a(27) =5103a(28) =7a(29) =1
External references
- oeis: A369919