2760615

Appears in sequences

• a(n) = (2*n)!*(2*n+1)! / (n! * (n+1)!)^2.at n=7A000891
• Successive denominators of Wallis's approximation to Pi/2 (reduced).at n=14A001902
• Coefficients of Legendre polynomials.at n=7A002463
• a(n) is the number of n-step walks on square lattice such that 0 <= y <= x at each step.at n=14A005558
• Triangle read by rows: T(n, k) = binomial(2*n+1, n-k)^2*(2*k+1)/(2*n+1).at n=28A067802
• Let W(n) = Product_{k=1..n} (1 - 1/(4*k^2)), the partial Wallis product (lim_{n->oo} W(n) = 2/Pi); then a(n) = numerator(W(n)).at n=7A069955
• Square array T(n,k) read by antidiagonals: number of tilings of an <n,k,n> hexagon.at n=38A103905
• Triangle of central coefficients of generalized Pascal-Narayana triangles.at n=47A120258
• Eighth column (and diagonal) of Narayana triangle A001263.at n=7A134289
• Moment sequence of tr(A^2) in USp(4).at n=14A138350
• Number of 7 X 7 matrices with elements in 0..n with each row and each column in nondecreasing order. 7,7,n can be permuted, see formula.at n=2A140911
• Array read by ascending antidiagonals: A(n, k) = (n + 1)*binomial(2*k + n - 1, k - 1)^2 / (2*k + n - 1) for k > 0, and A(n, 0) = 0.at n=44A378062
• a(n) = denominator(r(n)) where r(n) = (n/2)*(Pi/2)^cos(Pi*(n-1))*((n/2-1/2)!/(n/2)!)^2.at n=15A380950