a(n) = a(n-1) + a(n-2) - 2^(n-1) with a(0)=a(2)=0, a(1)=-a(3)=1, a(4)=-5.

Terms

a(0) =0a(1) =1a(2) =0a(3) =-1a(4) =-5a(5) =-14a(6) =-35a(7) =-81a(8) =-180a(9) =-389a(10) =-825a(11) =-1726a(12) =-3575a(13) =-7349a(14) =-15020a(15) =-30561a(16) =-61965a(17) =-125294a(18) =-252795a(19) =-509161a(20) =-1024100a(21) =-2057549a(22) =-4130225a(23) =-8284926a(24) =-16609455a(25) =-33282989a(26) =-66669660a(27) =-133507081a(28) =-267285605a(29) =-535010414