54179

Appears in sequences

• Join 2n points on a line with n arcs above the line; form graph with the arcs as nodes, joining 2 nodes when the arcs cross. a(n) is the number of cases in which the graph is symmetric about middle and has no isolated nodes.at n=9A008910
• G.f. satisfies A(x) = 1 + x (1+Sum_{n=0..inf} [xA(x)]^(2^n)).at n=16A075853
• Number of ordered triples (w,x,y) with all terms in {-n,...-1,1,...,n} and w+2x+3y>1.at n=24A211622
• a(n) = floor(M(g(n-1)+1, ..., g(n))), where M = harmonic mean and g(n) = n^3 + n^2 + n + 1.at n=37A227015