206977domain: NAppears in sequencesRow 4 of array in A047666.at n=27A047668Triangle, read by rows, T(n, k) = (2*n)!/((n-k)! * k!)^2 - (2*n)!/(n!)^2 + 1.at n=23A176078Triangle, read by rows, T(n, k) = (2*n)!/((n-k)! * k!)^2 - (2*n)!/(n!)^2 + 1.at n=25A176078