f(x)=x^n\cdot e^{-x}

n \in \{1,2,\dots, 6\}

e^x

x^6

n \in \{1,2,\dots, 6\}

l1 = Sequence(If[x > 0, x^(n), 0], n, 1, 6)
f(x) = exp(x)
g(x) = exp((-x))
l2 = Sequence((x^(n) * exp((-x))), n, 1, 6)
h(x) = x^(6)
A = Intersect(h, f, (16.998887352296055, 2.412809174704485E7))
a: 17^(2.412809175E7)
B = (3.7443584403678143, -2.0159028691326875E7)