13852815domain: NAppears in sequencesa(n) = (prime(n)^5 - prime(n)^4)/2.at n=10A138439Triangular array read by rows. T(n,k) is the number of labeled directed graphs on [n] with exactly k strongly connected components of size 1 with outdegree zero, n>=0, 0<=k<=n.at n=23A362013