A symmetrical triangle sequence: T(n, k) = q^k + q^(n-k) - q^n, with q=2.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =0a(5) =1a(6) =1a(7) =-2a(8) =-2a(9) =1a(10) =1a(11) =-6a(12) =-8a(13) =-6a(14) =1a(15) =1a(16) =-14a(17) =-20a(18) =-20a(19) =-14a(20) =1a(21) =1a(22) =-30a(23) =-44a(24) =-48a(25) =-44a(26) =-30a(27) =1a(28) =1a(29) =-62