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Infinite reciprocal summation (Posted on 2024-02-05) Difficulty: 3 of 5
Let a1=3/2 and an+1=a2n−an+1.

Compute the sum 1/a1+1/a2+1/a3+….

No Solution Yet Submitted by Danish Ahmed Khan    
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Solution Computer solution | Comment 1 of 2
Looks like the answer is 2
But I was not able to come  up with an analytic method.
-----------
def f(n):
    if n == 1:
        return 3/2
    return f(n-1)**2 - f(n-1) + 1

thesum = 0
for n in range(1, 14):
    thesum += 1/f(n)
    print(n, 1/f(n), thesum)

1 0.6666666666666666 0.6666666666666666
2 0.5714285714285714 1.2380952380952381
3 0.43243243243243246 1.6705276705276706
4 0.24782187802516942 1.9183495485528401
5 0.07548691107919238 1.9938364596320326
6 0.006125783851910988 1.9999622434839437
7 3.775509055601516e-05 1.9999999985744996
8 1.4255006807682198e-09 2.0000000000000004
9 2.03205219376735e-18 2.0000000000000004
10 4.1292361181946995e-36 2.0000000000000004
11 1.7050590919803628e-71 2.0000000000000004
12 2.9072265071448993e-142 2.0000000000000004
13 8.45196596384593e-284 2.0000000000000004

  Posted by Larry on 2024-02-05 08:33:44
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