a(n) = 10*n*(n+1).

Terms

a(0) =0a(1) =20a(2) =60a(3) =120a(4) =200a(5) =300a(6) =420a(7) =560a(8) =720a(9) =900a(10) =1100a(11) =1320a(12) =1560a(13) =1820a(14) =2100a(15) =2400a(16) =2720a(17) =3060a(18) =3420a(19) =3800a(20) =4200a(21) =4620a(22) =5060a(23) =5520a(24) =6000a(25) =6500a(26) =7020a(27) =7560a(28) =8120a(29) =8700