a(n) = binomial(2^n + 2*n, n).A132685a(n) = binomial(2^n + 2*n, n).Terms a(0) =1a(1) =4a(2) =28a(3) =364a(4) =10626a(5) =850668a(6) =218618940a(7) =198773423848External referencesoeis: A132685