cp's OEIS Frontend

A075581 Let 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).

%I A075581 #8 Jan 09 2021 11:04:45
%S A075581 1,4,16,80,448,2304,11520,67584,372736,1966080,11141120,63504384,
%T A075581 348651520,1917583360,11142168576,62704844800,343513497600,
%U A075581 1992378286080,11402534191104,63709397385216,361019918516224
%N A075581 Let 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).
%e A075581 P(3,X) = X^7 + X^6 - 24*X^5 - 24*X^4 + 80*X^3 + 80*X^2 - 64*X - 64, hence a(3) = 80.
%K A075581 easy,nonn
%O A075581 0,2
%A A075581 _Benoit Cloitre_, Oct 11 2002