(1,1) entry of powers of the orthogonal design shown below.

Terms

a(0) =-1a(1) =2a(2) =4a(3) =-56a(4) =80a(5) =-352a(6) =64a(7) =2176a(8) =-4864a(9) =31232a(10) =-23552a(11) =-14336a(12) =217088a(13) =-2056192a(14) =2375680a(15) =-7307264a(16) =-4390912a(17) =102367232a(18) =-169607168a(19) =877133824a(20) =-397410304a(21) =-3042967552a(22) =9265217536a(23) =-68308434944a(24) =62495129600a(25) =-78483816448a(26) =-342993403904