a(n) = Product_{k=0..n} (2^k + 4^(n-k)).A370014a(n) = Product_{k=0..n} (2^k + 4^(n-k)).Terms a(0) =2a(1) =15a(2) =510a(3) =84240a(4) =69204960a(5) =284844384000External referencesoeis: A370014