348651520domain: NAppears in sequencesa(n) = binomial(n,3)*2^(n-3).at n=18A001789Let P(n,X) = Product_{i=1..2n+1} (X - 1/cos(Pi*k/(2n+1))); then P(n,X) is a polynomial with integer coefficients. Sequences gives maximum values of absolute values of coefficients of P(n,X).at n=12A075581