perplexus.info :: Sequences : Fibo's common divider

Fibo's common divider (Posted on 2020-06-10)

1,1,2,3,5,8,13...

Given basic Fibonacci sequence (as above) with a₁=1 and a₂=1 evaluate the GCD of a₇₇₀ and a₁₀₀₀.

No Solution Yet Submitted by Ady TZIDON

Rating: 3.0000 (1 votes)

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computer solution

| Comment 2 of 4 |

5 point 200

10 Phi=(1+sqrt(5))/2

20 A=int(Phi^770/sqrt(5)+0.5)

30 B=int(Phi^1000/sqrt(5)+0.5)

40 print gcd(A,B)

finds the GCD is 55.

Posted by Charlie on 2020-06-10 19:18:12

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