solving euler series with python

Question

s(i+1) = ((si)^2 + 45) mod 1,000,000,007 this is one series for which my program works fine

s = [0,0] 
i = 1 
for i in range(1,5):
    s.append((pow(s[i],2) + 45) % 1000000007)
print s

values we are getting here are S = 0, 45, 2070, 4284945, 753524550, 478107844, 894218625 i.e. F(2) = 45, F(4) = 4284990 ..

Now we have F(10^2) = 26365463243, F(10^4) = 2495838522951.

By putting value of F(2) in equation (based on program), I am able to get value for F(4). But not same for F(10^2) to get value for F(10^4). Any hint for this?

Well, you are just showing the piece of code that is working fine. You should post how you are calculating F(x) — Ivo, Jul 31 '15 at 13:12
@Stiffo: I am not getting error, issue is can I apply same logic of F(2) for F(10) ? — puncrazy, Jul 31 '15 at 13:13
The code generates S not F. notice S(4) = 4284945 and F(4) = 4284990. They are not the same — Ivo, Jul 31 '15 at 13:18
Also you seem to do first adding 45 and then squaring it. the exercise says the other way around — Ivo, Jul 31 '15 at 13:22
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/84805/discussion-between-puncrazy-and-ivo-beckers). — puncrazy, Jul 31 '15 at 13:33

score 1 · Answer 1 · answered Jul 31 '15 at 13:12

1

Giving you hints will be dangerous... the project euler group might not be happy.

But I hope saying something like "Birthday paradox" won't be considered cheating... (anyway this is not even a hint to the best answer).

Enjoy your problem~

answered Jul 31 '15 at 13:12

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solving euler series with python

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