20760741domain: NAppears in sequencesa(n) = ((2*n+1)!!)^2 * (Sum_{k=1..n} 1/(2*k+1)^2).at n=5A335090Square array T(n,k), n>=0, k>=0, read by antidiagonals: T(n,k) = ((2n+1)!!)^k * Sum_{j=1..n} 1/(2*j+1)^k.at n=33A335095