44808domain: NAppears in sequencesNumbers k such that 7*10^k + 4*R_k - 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=16A103057Number of ordered triples (w,x,y) with all terms in {-n,...-1,1,...,n} and w^2>x^2+y^2.at n=28A211631Number of connected regular simple graphs on n labeled vertices.at n=7A322659