a(n) = n*(n+1)*(n+2)*(n+3)*(n+4)/8.

Terms

a(0) =0a(1) =15a(2) =90a(3) =315a(4) =840a(5) =1890a(6) =3780a(7) =6930a(8) =11880a(9) =19305a(10) =30030a(11) =45045a(12) =65520a(13) =92820a(14) =128520a(15) =174420a(16) =232560a(17) =305235a(18) =395010a(19) =504735a(20) =637560a(21) =796950a(22) =986700a(23) =1210950a(24) =1474200a(25) =1781325a(26) =2137590a(27) =2548665a(28) =3020640a(29) =3560040