a(n) = (n+1)*(n+2)^2*(n+3)^2*(n+4)^2*(n+5)^2*(n+6)/86400.

Terms

a(0) =1a(1) =21a(2) =196a(3) =1176a(4) =5292a(5) =19404a(6) =60984a(7) =169884a(8) =429429a(9) =1002001a(10) =2186184a(11) =4504864a(12) =8836464a(13) =16604784a(14) =30046752a(15) =52581816a(16) =89311761a(17) =147685461a(18) =238369516a(19) =376372920a(20) =582481900a(21) =885069900a(22) =1322357400a(23) =1945206900a(24) =2820550005a(25) =4035556161a(26) =5702666256a(27) =7965629056