401998

Appears in sequences

• Number of perfect matchings in the graph C_7 X C_{2n}.at n=1A230033
• Number of perfect matchings in the graph C_6 x C_n.at n=4A232804
• a(n) = ( Product_{j=1..n} Product_{k=1..n+1} (4*sin((2*j-1)*Pi/n)^2 + 4*sin((2*k-1)*Pi/(n+1))^2) )^(1/4).at n=6A341493
• Square array T(n,k), n >= 1, k >= 1, read by antidiagonals, where T(n,k) = sqrt( Product_{a=1..n} Product_{b=1..k} (4*sin((2*a-1)*Pi/(2*n))^2 + 4*sin((2*b-1)*Pi/k)^2) ).at n=38A341533
• Square array T(n,k), n >= 1, k >= 1, read by antidiagonals downwards: number of perfect matchings in the graph C_{2n} x C_k.at n=38A341741