88101

Appears in sequences

• Number T(n,k) of permutations p of [n] such that the up-down signature of 0,p has nonnegative partial sums with a maximal value of k; triangle T(n,k), n>=0, 0<=k<=n, read by rows.at n=48A258829
• Number of permutations p of [n] such that the up-down signature of 0,p has nonnegative partial sums with a maximal value of three.at n=6A316390
• Number of n-vertex, 2-edge multigraphs that are not nesting. Number of n-vertex, 2-edge multigraphs that are not crossing.at n=27A326278
• a(n) = Sum_{k=1..n} tan(k*Pi/(1+2*n))^4.at n=13A377858