a(n) = (n^10 + n^5)/2.

Terms

a(0) =0a(1) =1a(2) =528a(3) =29646a(4) =524800a(5) =4884375a(6) =30236976a(7) =141246028a(8) =536887296a(9) =1743421725a(10) =5000050000a(11) =12968792826a(12) =30958806528a(13) =68929431571a(14) =144627596400a(15) =288325575000a(16) =549756338176