a(0)=a(1)=1, a(n) = 2*a(n-1)- A010686(n), n>1.

Terms

a(0) =1a(1) =1a(2) =1a(3) =-3a(4) =-7a(5) =-19a(6) =-39a(7) =-83a(8) =-167a(9) =-339a(10) =-679a(11) =-1363a(12) =-2727a(13) =-5459a(14) =-10919a(15) =-21843a(16) =-43687a(17) =-87379a(18) =-174759a(19) =-349523a(20) =-699047a(21) =-1398099a(22) =-2796199a(23) =-5592403a(24) =-11184807a(25) =-22369619a(26) =-44739239a(27) =-89478483a(28) =-178956967a(29) =-357913939