1171390

Appears in sequences

• Number of 3-element ordered antichains on an unlabeled n-element set; T_1-hypergraphs with 3 labeled nodes and n hyperedges.at n=22A056005
• Coefficients T(n,k) of x^n*y^k in A(x,y) for n >= 0, k = 0..3*n+1, where A(x,y) satisfies: y = Sum_{n=-oo..+oo} (-x)^(n^2) * A(x,y)^((n-1)^2), as an irregular triangle read by rows.at n=121A356500
• G.f. satisfies A(x) = 1 + x^4*A(x)^3*(1 + x*A(x)).at n=33A365729