Nth Even Fibonacci Number.

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**The Fibonacci numbers are the numbers in the following integer sequence.**

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ………

**In mathematical terms, the sequence Fn of Fibonacci numbers is defined by the recurrence relation**

```
Fn = Fn-1 + Fn-2 with seed values
F0 = 0 and F1 = 1.
```

**The even number Fibonacci sequence is : 0, 2, 8, 34, 144, 610, 2584…. We have to find nth number in this sequence.**

```
The formula of even Fibonacci number = ((4*evenFib(n-1)) + evenFib(n-2));
```

**You can more details on geeksforgeeks post.**

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Even i used the same code in geeksforgeeks i am getting tle for finding nth even fibonacci .

any help is appreciated.

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Notice that every 3rd number is even. So you can find the real index and then use matrix expo

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