Given a number N, the task is to find Nth Enneacontagon number.
A Enneacontagon number. is class of figurate number. It has 90 – sided polygon called enneacontagon. The N-th enneacontagon number count’s the 90 number of dots and all others dots are surrounding with a common sharing corner and make a pattern. The first few enneacontagonol numbers are 1, 90, 267, 532 …
Examples:
Input: N = 2
Output: 90
Explanation:
The second enneacontagonol number is 90.
Input: N = 3
Output: 267
Approach: The N-th enneacontagon number is given by the formula:
- Nth term of s sided polygon =
- Therefore Nth term of 90 sided polygon is
Below is the implementation of the above approach:
C++
// C++ program for above approach #include <bits/stdc++.h> using namespace std; // Finding the nth enneacontagon Number int enneacontagonNum( int n) { return (88 * n * n - 86 * n) / 2; } // Driver Code int main() { int n = 3; cout << "3rd enneacontagon Number is = " << enneacontagonNum(n); return 0; } // This code is contributed by Akanksha_Rai |
C
// C program for above approach #include <stdio.h> #include <stdlib.h> // Finding the nth enneacontagon Number int enneacontagonNum( int n) { return (88 * n * n - 86 * n) / 2; } // Driver program to test above function int main() { int n = 3; printf ( "3rd enneacontagon Number is = %d" , enneacontagonNum(n)); return 0; } |
Java
// Java program for above approach class GFG{ // Finding the nth enneacontagon number public static int enneacontagonNum( int n) { return ( 88 * n * n - 86 * n) / 2 ; } // Driver code public static void main(String[] args) { int n = 3 ; System.out.println( "3rd enneacontagon Number is = " + enneacontagonNum(n)); } } // This code is contributed by divyeshrabadiya07 |
Python3
# Python3 program for above approach # Finding the nth enneacontagon Number def enneacontagonNum(n): return ( 88 * n * n - 86 * n) / / 2 # Driver Code n = 3 print ( "3rd enneacontagon Number is = " , enneacontagonNum(n)) # This code is contributed by divyamohan123 |
C#
// C# program for above approach using System; class GFG{ // Finding the nth enneacontagon number public static int enneacontagonNum( int n) { return (88 * n * n - 86 * n) / 2; } // Driver code public static void Main(String[] args) { int n = 3; Console.WriteLine( "3rd enneacontagon Number is = " + enneacontagonNum(n)); } } // This code is contributed by Rajput-Ji |
Javascript
<script> // JavaScript program for above approach // Finding the nth enneacontagon Number function enneacontagonNum(n) { return (88 * n * n - 86 * n) / 2; } // Driver Code var n = 3; document.write( "3rd enneacontagon Number is = " + enneacontagonNum(n)); </script> |
3rd enneacontagon Number is = 267
Time Complexity: O(1)
Auxiliary Space: O(1)
Reference: https://en.wikipedia.org/wiki/Enneacontagon
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