a(n) = (n+1)*binomial(n+1,16).

Terms

a(0) =16a(1) =289a(2) =2754a(3) =18411a(4) =96900a(5) =427329a(6) =1641486a(7) =5638611a(8) =17651304a(9) =51074375a(10) =138105110a(11) =352023165a(12) =851809140a(13) =1968053535a(14) =4362680250a(15) =9316746045a(16) =19234572480a(17) =38504502630a(18) =74934688620a(19) =142097513250a(20) =263083395960a(21) =476403662790a(22) =845119028340