I just need a formula. I have been googling for about an hour and don't see anything that I can apply to the calculator. I have made a program that does the nth term but adding them up is giving me trouble.

Thanks!

Thanks!

I just need a formula. I have been googling for about an hour and don't see anything that I can apply to the calculator. I have made a program that does the nth term but adding them up is giving me trouble.

Thanks!

Thanks!

Do you mind sharing your program code or even the language it's written in? It could be as simple as adding all the numbers to a list and then summing the elements of the list. It's been a while but in TI-BASIC it should be sum(

I did it in TI-Basic and I don't mind sharing the code, but I'm not near my calculator right now.

I was looking for a formula similar to that of an arithmetic series

**Code:**

I was looking for a formula similar to that of an arithmetic series

`(n/2)(A₁ + A(sub n))`

Does this not work?

http://stackoverflow.com/questions/4357223/finding-the-sum-of-fibonacci-numbers

You could use Binet's formula to calculate fibonacci numbers as well: http://en.wikipedia.org/wiki/Fibonacci_number#Closed-form_expression

http://stackoverflow.com/questions/4357223/finding-the-sum-of-fibonacci-numbers

You could use Binet's formula to calculate fibonacci numbers as well: http://en.wikipedia.org/wiki/Fibonacci_number#Closed-form_expression

So I could prompt user for last and first numbers in the sequence then do (binetsFormula(last)-binetsFormula(first)-2)?

Sum the first N Fibonacci numbers (assuming that your indexing is such that 0,1,1 are the 0th,1st,2nd elements of the series):

**Code:**

So if you want to sum the Mth-Nth Fibonacci numbers (inclusively)

**Code:**

```
```

.5(1+sqrt(5

int(~.5+(Ans^(N+2))/sqrt(5

So if you want to sum the Mth-Nth Fibonacci numbers (inclusively)

```
```

.5(1+sqrt(5

int(~.5+(Ans^(N+2))/sqrt(5))-int(~.5+(Ans^(M+1))/sqrt(5

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