Number of 9-ary heaps on n elements.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =24a(6) =120a(7) =720a(8) =5040a(9) =40320a(10) =362880a(11) =1814400a(12) =13305600a(13) =119750400a(14) =1245404160a(15) =14529715200a(16) =186810624000