[math-fun] Periodic Antisymmetric Matrices counted by Hermitte Numbers

Antisymmetric: Transpose(A)= -A, so zero diagonals Periodic: some matrix power = Identity Matrix A067994= Hermitte Numbers= 1,0,2,0,12,0,120,0,1680, ... Their periods are all 4. Strong law of small numbers checked upto n=8. Who says this is self-evident? W.