a(n) = Pi * n^2 rounded off.

Terms

a(0) =0a(1) =3a(2) =13a(3) =28a(4) =50a(5) =79a(6) =113a(7) =154a(8) =201a(9) =254a(10) =314a(11) =380a(12) =452a(13) =531a(14) =616a(15) =707a(16) =804a(17) =908a(18) =1018a(19) =1134a(20) =1257a(21) =1385a(22) =1521a(23) =1662a(24) =1810a(25) =1963a(26) =2124a(27) =2290a(28) =2463a(29) =2642