Triangle of Ward numbers T(n,k) read by rows.

Terms

a(0) =1a(1) =1a(2) =3a(3) =1a(4) =10a(5) =15a(6) =1a(7) =25a(8) =105a(9) =105a(10) =1a(11) =56a(12) =490a(13) =1260a(14) =945a(15) =1a(16) =119a(17) =1918a(18) =9450a(19) =17325a(20) =10395a(21) =1a(22) =246a(23) =6825a(24) =56980a(25) =190575a(26) =270270a(27) =135135a(28) =1a(29) =501