36300541200domain: NAppears in sequencesa(n) = Sum_{j=0..n} (n+j)*binomial(n+j,j).at n=16A002737a(n) = 4*C(2n,n) - 3*0^n.at n=18A146534a(n) = 4*(2*n)! / (n!)^2.at n=18A240530