a(n) = Re(b(n)) where b(n)=(1+i)*b(n-1)+b(n-2), with b(1)=0, b(2)=1.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =0a(5) =-3a(6) =-9a(7) =-19a(8) =-32a(9) =-43a(10) =-39a(11) =5a(12) =128a(13) =377a(14) =783a(15) =1305a(16) =1728a(17) =1513a(18) =-367a(19) =-5495a(20) =-15744a(21) =-32267a(22) =-53177a(23) =-69371a(24) =-58464a(25) =21693a(26) =235305a(27) =656909a(28) =1328896a(29) =2165489