a(n) = 2*n^2.

Terms

a(0) =0a(1) =2a(2) =8a(3) =18a(4) =32a(5) =50a(6) =72a(7) =98a(8) =128a(9) =162a(10) =200a(11) =242a(12) =288a(13) =338a(14) =392a(15) =450a(16) =512a(17) =578a(18) =648a(19) =722a(20) =800a(21) =882a(22) =968a(23) =1058a(24) =1152a(25) =1250a(26) =1352a(27) =1458a(28) =1568a(29) =1682