128*n^8 - 256*n^6 + 160*n^4 - 32*n^2 + 1.

Terms

a(0) =1a(1) =1a(2) =18817a(3) =665857a(4) =7380481a(5) =46099201a(6) =203253121a(7) =708158977a(8) =2081028097a(9) =5374978561a(10) =12545596801a(11) =26986755841a(12) =54276558337a(13) =103182433537a(14) =186979578241a(15) =325142092801a(16) =545471324161a(17) =886731088897