a(n) = binomial(2*n^2, n).A264411a(n) = binomial(2*n^2, n).Terms a(0) =1a(1) =2a(2) =28a(3) =816a(4) =35960a(5) =2118760a(6) =156238908a(7) =13834413152External referencesoeis: A264411