a(n) = 5*(3*n+1)*(9*n+8)/2 (n>=0).

Terms

a(0) =20a(1) =170a(2) =455a(3) =875a(4) =1430a(5) =2120a(6) =2945a(7) =3905a(8) =5000a(9) =6230a(10) =7595a(11) =9095a(12) =10730a(13) =12500a(14) =14405a(15) =16445a(16) =18620a(17) =20930a(18) =23375a(19) =25955a(20) =28670a(21) =31520a(22) =34505a(23) =37625a(24) =40880a(25) =44270a(26) =47795a(27) =51455a(28) =55250a(29) =59180