# Let Fn denote the nth Fibonacci number. If we know that F24=46368 and F28=317811, compute F26?

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Assumptions
A Fibonacci sequence is a sequence that satisfy the recurrence relation Fn+2 = Fn+1 + Fn for with initial conditions F1=F2=1

posted Jun 24, 2015

We know F(n)= F(n-1) + F(n-2)

;;;;;; F28=F27 + F26 ;;;;F27=F26 + F25 ;;;;; F26= F25 + F24;;;;

Rearranging we get ;;; F26=(F28+F24)/3 === 121393

Similar Puzzles

Let us say there are two natural numbers "L" and "R".
We performed eight operations on these two numbers as

Step-1: L = R
Step-2: L x L = R x L
Step-3: L^2 - R^2 = LR - R^2
Step-4: (L + R)( L - R) = R(L - R)
Step-5: L + R = R
Step-6: R + R = R
Step-7: 2R = R
Step- 8: 2 = 1

What is wrong here?

Can you find a number such that if we multiply that number by 1 or 2 or 3 or 4 or 5 or 6, then the resultant number contains same all digits (of course in a different place)

–1 vote

According to number theory of mathematics , a perfect number is a positive integer that is equal to the sum of its positive divisors excluding the number itself.
For example :
6 => 1+2+3
28 =>1+2+4+7+14

I know one more number that is a perfect number and contains not more than 2 digits (i.e 496 won't be consider as it contains 3 digits).

Find the number ?