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

Terms

a(0) =1a(1) =1a(2) =-80a(3) =1a(4) =626a(5) =-80a(6) =-2400a(7) =1a(8) =6481a(9) =626a(10) =-14640a(11) =-80a(12) =28562a(13) =-2400a(14) =-50080a(15) =1a(16) =83522a(17) =6481a(18) =-130320a(19) =626a(20) =192000a(21) =-14640a(22) =-279840a(23) =-80a(24) =391251a(25) =28562a(26) =-524960a(27) =-2400a(28) =707282a(29) =-50080