Sum_{k=1..2n-1} J(4*n,k)*k^2, where J(i,j) is the Jacobi symbol.

Terms

a(0) =1a(1) =-8a(2) =-24a(3) =84a(4) =24a(5) =-144a(6) =-224a(7) =32a(8) =654a(9) =-560a(10) =-616a(11) =96a(12) =312a(13) =-1120a(14) =-1440a(15) =5456a(16) =-272a(17) =-288a(18) =-2888a(19) =96a(20) =1008a(21) =-4048a(22) =-3680a(23) =576a(24) =16700a(25) =-5200a(26) =-216a(27) =896a(28) =2088a(29) =-8160