60940domain: NAppears in sequencesNumbers k such that k*2^k - k - 1 is prime.at n=27A046843E.g.f. satisfies A(x) = 1 - log(1 - x*A(x)^2)/A(x).at n=6A365438Number of finite regions in a complete bipartite graph where the n vertices of each part are placed on the vertices, and on opposite sides, of a regular 2n-gon.at n=22A392972