455805857978domain: NAppears in sequencesa(n) is the constant term in expansion of Product_{ k = 1..n } (x^k + 1/x^k)^3.at n=15A124995Maximal coefficient of (1 + x)^3 * (1 + x^2)^3 * (1 + x^3)^3 * ... * (1 + x^n)^3.at n=15A369709