Permutations, Combinations and Series - General Aptitude - General Aptitude (GA) Previous Year Questions

Three distinct sets of indistinguishable twins are to be seated at a circular table that has 8 identical chairs. Unique seating arrangements are defined by the relative positions of the people.
How many unique seating arrangements are possible such that each person is sitting next to their twin?

A ‘frabjous’ number is defined as a 3 digit number with all digits odd, and no two adjacent digits being the same. For example, 137 is a frabjous number, while 133 is not. How many such frabjous numbers exist?

Ankita has to climb 5 stairs starting at the ground, while respecting the following rules:
1. At any stage, Ankita can move either one or two stairs up.
2. At any stage, Ankita cannot move to a lower step.
Let \(F(N)\) denote the number of possible ways in which Ankita can reach the \(N^{th}\) stair. For example, \(F(1) = 1\), \(F(2) = 2\), \(F(3) = 3\).
The value of \(F(5)\) is ______.