Surround numbers of an n X 2 rectangle when n is even.

Terms

a(0) =224a(1) =705a(2) =1600a(3) =3065a(4) =5280a(5) =8449a(6) =12800a(7) =18585a(8) =26080a(9) =35585a(10) =47424a(11) =61945a(12) =79520a(13) =100545a(14) =125440a(15) =154649a(16) =188640a(17) =227905a(18) =272960a(19) =324345a(20) =382624a(21) =448385a(22) =522240a(23) =604825a(24) =696800a(25) =798849a(26) =911680a(27) =1036025a(28) =1172640a(29) =1322305