a(n) = binomial(n+2,n)*binomial(n+6,n).

Terms

a(0) =1a(1) =21a(2) =168a(3) =840a(4) =3150a(5) =9702a(6) =25872a(7) =61776a(8) =135135a(9) =275275a(10) =528528a(11) =965328a(12) =1689324a(13) =2848860a(14) =4651200a(15) =7379904a(16) =11415789a(17) =17261937a(18) =25573240a(19) =37191000a(20) =53183130a(21) =74890530a(22) =103980240a(23) =142506000a(24) =192976875a(25) =258434631a(26) =342540576a(27) =449672608a(28) =585033240a(29) =754769400