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

Terms

a(0) =0a(1) =8a(2) =40a(3) =120a(4) =280a(5) =560a(6) =1008a(7) =1680a(8) =2640a(9) =3960a(10) =5720a(11) =8008a(12) =10920a(13) =14560a(14) =19040a(15) =24480a(16) =31008a(17) =38760a(18) =47880a(19) =58520a(20) =70840a(21) =85008a(22) =101200a(23) =119600a(24) =140400a(25) =163800a(26) =190008a(27) =219240a(28) =251720a(29) =287680