a(n) = Sum_{d|n, n/d=1 mod 4} d^4 - Sum_{d|n, n/d=3 mod 4} d^4.

Terms

a(0) =1a(1) =16a(2) =80a(3) =256a(4) =626a(5) =1280a(6) =2400a(7) =4096a(8) =6481a(9) =10016a(10) =14640a(11) =20480a(12) =28562a(13) =38400a(14) =50080a(15) =65536a(16) =83522a(17) =103696a(18) =130320a(19) =160256a(20) =192000a(21) =234240a(22) =279840a(23) =327680a(24) =391251a(25) =456992a(26) =524960a(27) =614400a(28) =707282a(29) =801280