a(n) = 3*binomial(n+1,7).

Terms

a(0) =3a(1) =24a(2) =108a(3) =360a(4) =990a(5) =2376a(6) =5148a(7) =10296a(8) =19305a(9) =34320a(10) =58344a(11) =95472a(12) =151164a(13) =232560a(14) =348840a(15) =511632a(16) =735471a(17) =1038312a(18) =1442100a(19) =1973400a(20) =2664090a(21) =3552120a(22) =4682340a(23) =6107400a(24) =7888725a(25) =10097568a(26) =12816144a(27) =16138848a(28) =20173560a(29) =25043040