f_0 = Function(ℯ^(1 - x), 0, 1)
I_0 = Integral(f_0, 0, 1)
f_1(x) = If[0 ≤ x ≤ 1, (x * ℯ^(1 - x))]
I_1 = Integral(f_1, 0, 1)
f_2(x) = If[0 ≤ x ≤ 1, (x^(2) * ℯ^(1 - x) / 2)]
I_2 = Integral(f_2, 0, 1)
f_3(x) = If[0 ≤ x ≤ 1, (x^(3) * ℯ^(1 - x) / 6)]
I_3 = Integral(f_3, 0, 1)
a_3: I_2 - I_3
a_2: I_1 - I_2
a_1: I_0 - I_1
f_4(x) = If[0 ≤ x ≤ 1, (x^(4) * ℯ^(1 - x) / 24)]
I_4 = Integral(f_4, 0, 1)
a_4: I_3 - I_4
f = Function(f_1, 0, 1)
A1 = 0
A2: A1 + 1
A3: A2 + 1
A4: A3 + 1
A5: A4 + 1
A6: A5 + 1
A7: A6 + 1
A8: A7 + 1
A9: A8 + 1
A10: A9 + 1
A11: A10 + 1
A12: A11 + 1
A13: A12 + 1
A14: A13 + 1
A15: A14 + 1
A16: A15 + 1
A17: A16 + 1
A18: A17 + 1
A19: A18 + 1
A20: A19 + 1
B1 = Sum(Sequence[1 / k!, k, 0, A1])
B2 = Sum(Sequence[1 / k!, k, 0, A2])
B3 = Sum(Sequence[1 / k!, k, 0, A3])
B4 = Sum(Sequence[1 / k!, k, 0, A4])
B5 = Sum(Sequence[1 / k!, k, 0, A5])
B6 = Sum(Sequence[1 / k!, k, 0, A6])
B7 = Sum(Sequence[1 / k!, k, 0, A7])
B8 = Sum(Sequence[1 / k!, k, 0, A8])
B9 = Sum(Sequence[1 / k!, k, 0, A9])
B10 = Sum(Sequence[1 / k!, k, 0, A10])
B11 = Sum(Sequence[1 / k!, k, 0, A11])
B12 = Sum(Sequence[1 / k!, k, 0, A12])
B13 = Sum(Sequence[1 / k!, k, 0, A13])
B14 = Sum(Sequence[1 / k!, k, 0, A14])
B15 = Sum(Sequence[1 / k!, k, 0, A15])
B16 = Sum(Sequence[1 / k!, k, 0, A16])
B17 = Sum(Sequence[1 / k!, k, 0, A17])
B18 = Sum(Sequence[1 / k!, k, 0, A18])
B19 = Sum(Sequence[1 / k!, k, 0, A19])
B20 = Sum(Sequence[1 / k!, k, 0, A20])