Signed generalized Fibonacci numbers.

Terms

a(0) =1a(1) =-2a(2) =7a(3) =-26a(4) =107a(5) =-468a(6) =2141a(7) =-10124a(8) =49101a(9) =-242934a(10) =1221427a(11) =-6222838a(12) =32056215a(13) =-166690696a(14) =873798681a(15) =-4612654808a(16) =24499322137a(17) =-130830894666a(18) =702037771647