a(n) = Sum_{k=0..n} (-2)^k * |(n - k | k)|, where (a | b) denotes the Kronecker symbol.

Terms

a(0) =0a(1) =-1a(2) =-2a(3) =2a(4) =-10a(5) =10a(6) =-34a(7) =42a(8) =-170a(9) =114a(10) =-650a(11) =682a(12) =-2210a(13) =2730a(14) =-10794a(15) =6290a(16) =-43690a(17) =43690a(18) =-141474a(19) =174762a(20) =-666250a(21) =449778a(22) =-2794154a(23) =2796202a(24) =-9054370a(25) =10168010a(26) =-44731050a(27) =29826162a(28) =-176859690a(29) =178956970