1,0,0,1,1,0,0…… The general term formula of It's best to use the method I know. I'm a freshman in senior high school and only know trigonometric function

1,0,0,1,1,0,0…… The general term formula of It's best to use the method I know. I'm a freshman in senior high school and only know trigonometric function

I only know trigonometric function. That's me. An = | sin (n (n + 1) π / 4) |, | |It's absolute