a(n) = ((6n-5)!!!+(6n-4)!!!)/(6n-3).A274117a(n) = ((6n-5)!!!+(6n-4)!!!)/(6n-3).Terms a(0) =1a(1) =12a(2) =1064a(3) =252160a(4) =115315200a(5) =86449126400External referencesoeis: A274117