Fibonacci, triangular, square, cube, pentagon numbers

Fibonacci number is N, iff 5N^2 - 4 OR 5N^2+4 is a perfect square.

Triangular number are of n(n+1) / 2
eg. 1,3,6,10,15….

Square number : N^2

Cube: N^3

See also

• For a Given node of a binary tree, print the K distance nodes.
• Find the distance between 2 nodes in Binary Tree
• Find the distance between 2 nodes in Binary Tree
• Program to count leaf nodes in a binary tree
• Friend Circle - Hackerrank