21395520

Appears in sequences

• First numerator and then denominator of the central elements of the 1/5-Pascal triangle (by row).at n=28A046610
• First denominator and then numerator of the central elements of the 1/5-Pascal triangle (by row).at n=29A046611
• Distinct numbers in writing first numerator and then denominator of the central elements of the 1/5-Pascal triangle (by row).at n=14A046612
• G.f. A(x) = 1 + 4*x*A(x)^(1/2); A(x) = 1 + 8*x^2 + 4*x*sqrt(1 + 4*x^2).at n=31A135863
• Square array read by ascending antidiagonals: T(n,k) = (2*k)!/k!^2 * ( (2*n*k)! * ((n + 2)*k)! )/( (n*k)! * ((n + 1)*k)!^2 ) for n, k > = 0.at n=38A364509