Program to check if N is a Icosihenagonal number
Given an integer N, the task is to check if it is a Icosihenagonal number or not.
Icosihenagonal number is class of figurate number. It has 21 – sided polygon called Icosihenagon. The n-th Icosihenagonal number counts the 21 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few Icosihenagonal numbers are 1, 21, 60, 118, 195, 291, 406…
Input: N = 21
Second icosihenagonal number is 21.
Input: N = 30
- The Kth term of the icosihenagonal number is given as
- As we have to check that the given number can be expressed as a icosihenagonal number or not. This can be checked as follows –
- Finally, check the value of computed using this formulae is an integer, which means that N is a icosihenagonal number.
Below is the implementation of the above approach:
Time Complexity: O(1)
Auxiliary Space: O(1)
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