136332

Appears in sequences

• Number of 3-element proper antichains (i.e., antichains such that every two members have nonempty intersection) on an unlabeled n-element set.at n=21A056782
• Number of preferential arrangements (or simple hierarchies) of 2*n labeled elements with two kinds of elements (where each kind has n elements).at n=5A099880
• Triangle arising in the computation of hypersigma, definition 2 (A191161).at n=50A202687
• Triangle relating to ordered Bell numbers, A000670.at n=50A208744
• Triangular array T(n,k) read by rows: column k is the expansion of e.g.f: exp(-2*x)*(exp(x)-1)^k/(2-exp(x)).at n=39A372245
• Expansion of e.g.f. 1 / sqrt(1 - x^3 * (exp(x) - 1)).at n=9A375718