a(n) = (8*n)!*n!/((4*n)!*(3*n)!*(2*n)!).A211420a(n) = (8*n)!*n!/((4*n)!*(3*n)!*(2*n)!).Terms a(0) =1a(1) =140a(2) =60060a(3) =29745716a(4) =15628090140External referencesoeis: A211420