866761domain: NAppears in sequencesa(n) = n^4 - 2*n^3 + 3*n^2 - 2*n + 1, the Alexander polynomial for reef and granny knots.at n=31A058031Number of n X 5 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 0 1 1 vertically.at n=11A208552G.f.: 1 / AGM(1-21*x, sqrt((1-9*x)*(1-49*x))).at n=4A246906