a(n) = (4n+2)^3.

Terms

a(0) =8a(1) =216a(2) =1000a(3) =2744a(4) =5832a(5) =10648a(6) =17576a(7) =27000a(8) =39304a(9) =54872a(10) =74088a(11) =97336a(12) =125000a(13) =157464a(14) =195112a(15) =238328a(16) =287496a(17) =343000a(18) =405224a(19) =474552a(20) =551368a(21) =636056a(22) =729000a(23) =830584a(24) =941192a(25) =1061208a(26) =1191016