BCMaclaurin series (Taylor series centered at a = 0)
f(x) = e^xP_{3}(x)
Maclaurin polynomial, degree 3
P_{3}(x) = 1 + x + \frac{x^2}{2!} + \frac{x^3}{3!}

Converges to f(x) = e^x on (-\infty, \infty).

f(0.5)
1.6487
P_3(0.5)
1.6458
error
0.0029

Every coefficient is c_k = \dfrac{f^{(k)}(0)}{k!}. That is why raising the degree adds one more term and pulls P_{3} closer to the curve.

kf^{(k)}(0)k!c_k = f^{(k)}(0)/k!
0111
1111
212\frac{1}{2}
316\frac{1}{6}
4124\frac{1}{24}

Taylor Series Builder: Coefficients from Derivatives from CalcLearn, free AP Calculus study tools.