Expansion of bracket function.

Terms

a(0) =1a(1) =1a(2) =-1a(3) =2a(4) =-5a(5) =13a(6) =-33a(7) =80a(8) =-184a(9) =402a(10) =-840a(11) =1699a(12) =-3382a(13) =6750a(14) =-13716a(15) =28550a(16) =-60587a(17) =129579a(18) =-275915a(19) =579828a(20) =-1197649a(21) =2431775a(22) =-4870105a(23) =9672634a(24) =-19173013a(25) =38151533a(26) =-76521331a(27) =154941608a(28) =-316399235a(29) =649807589