81730

Appears in sequences

• Number of 3-covers of an unlabeled n-set.at n=23A005783
• Riordan array [1,log(sec(x)+tan(x))].at n=71A147312
• Triangle read by rows: T(n,k) is the number of cycle-up-down permutations of {1,2,...,n} having k excedances (0<=k<=floor(n/2)).at n=33A186368