9381251041domain: NAppears in sequencesa(n) = (F(8*n+3) + F(8*n+1))/3, where F = A000045 (the Fibonacci sequence).at n=6A049676a(n) = L(4*n+2)/3, where L=A000032 (the Lucas sequence).at n=12A049685Expansion of (x-x^3)/(1-3*x+2*x^2-3*x^3+x^4).at n=25A140824a(n) = Product_{k=1..(n-1)/2} (5 + 4*cos(k*Pi/n)^2).at n=25A152119