Sum of positive even numbers up to n^2.

Terms

a(0) =0a(1) =6a(2) =20a(3) =72a(4) =156a(5) =342a(6) =600a(7) =1056a(8) =1640a(9) =2550a(10) =3660a(11) =5256a(12) =7140a(13) =9702a(14) =12656a(15) =16512a(16) =20880a(17) =26406a(18) =32580a(19) =40200a(20) =48620a(21) =58806a(22) =69960a(23) =83232a(24) =97656a(25) =114582a(26) =132860a(27) =154056a(28) =176820a(29) =202950