1876446

Appears in sequences

• a(n) = 2*3^n*(2*n)!/(n!*(n+2)!).at n=8A000168
• Square array T(n,k), read by antidiagonals: number of labeled trees, with increments of labels along edges constrained to -1,0,1, with n nodes that have no label greater than k.at n=44A101486
• Triangle T(n,k) read by rows: T(n,k) is the number of rooted genus-k maps with n edges, n>=0, 0<=k<=n.at n=36A238396
• Triangle read by rows: T(n,g) is the number of rooted maps with n edges on an orientable surface of genus g.at n=20A269919