e1

A1 = 0
A2 = 1
A3: 2.0 * A2 - A1
A4: 2.0 * A3 - A2
A5: 2.0 * A4 - A3
A6: 2.0 * A5 - A4
A7: 2.0 * A6 - A5
A8: 2.0 * A7 - A6
A9: 2.0 * A8 - A7
A10: 2.0 * A9 - A8
A11: 2.0 * A10 - A9
A12: 2.0 * A11 - A10
A13: 2.0 * A12 - A11
A14: 2.0 * A13 - A12
B1 = 0
B2: B1 + A2
B3: B2 + A3
B4: B3 + A4
B5: B4 + A5
B6: B5 + A6
B7: B6 + A7
B8: B7 + A8
B9: B8 + A9
B10: B9 + A10
B11: B10 + A11
B12: B11 + A12
B13: B12 + A13
B14: B13 + A14
P_1: (A1, B1)
P_2: (A2, B2)
P_3: (A3, B3)
P_4: (A4, B4)
P_5: (A5, B5)
P_6: (A6, B6)
P_7: (A7, B7)
P_8: (A8, B8)
P_9: (A9, B9)
P_{10}: (A10, B10)
P_{11}: (A11, B11)
P_{12}: (A12, B12)
P_{13}: (A13, B13)
P_{14}: (A14, B14)
L_1: {P_1, P_2, P_3, P_4, P_5, P_6, P_7, P_8, P_9, P_{10}, P_{11}, P_{12}, P_{13}, P_{14}}
N = 5 (slider from 0 to 8, step 1)
L1 = 0
f = FitPoly(L_1, N)