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

Terms

a(0) =1a(1) =-6a(2) =-20a(3) =8a(4) =176a(5) =288a(6) =-832a(7) =-3968a(8) =-1280a(9) =29184a(10) =68608a(11) =-96256a(12) =-741376a(13) =-712704a(14) =4505600a(15) =14712832a(16) =-6619136a(17) =-130940928a(18) =-208928768a(19) =629669888a(20) =2930769920a(21) =824180736a(22) =-21797797888a(23) =-50189041664a(24) =74004299776a(25) =549520932864a(26) =507007467520