Centered decagonal number
Given a number n, find the nth Centered decagonal number .
A Centered Decagonal Number is centered figurative number that represents a decagon with dot in center and all other dot surrounding it in successive decagonal form. Source[Wiki].
The first few Centered Decagonal Numbers are :
1, 11, 31, 61, 101, 151, 211, 281, 361, 451, 551, 661…………
Examples :
Input : 3
Output : 31
Input : 6
Output : 151
In mathematics centered decagonal number for n-th term is given by :
Below is the basic implementation of the above idea.
C++
#include <bits/stdc++.h>
using namespace std;
int centereddecagonalnum( int n)
{
return (5 * n * n + 5 * n + 1);
}
int main()
{
int n = 5;
cout << n << "th centered decagonal"
<< "number: " ;
cout << centereddecagonalnum(n);
cout << endl;
n = 9;
cout << n << "th centered decagonal"
<< "number: " ;
cout << centereddecagonalnum(n);
return 0;
}
|
C
#include <stdio.h>
int centereddecagonalnum( int n)
{
return (5 * n * n + 5 * n + 1);
}
int main()
{
int n = 5;
printf ( "%dth centered decagonal number: " ,n);
printf ( "%d\n" ,centereddecagonalnum(n));
n = 9;
printf ( "%dth centered decagonal number: " ,n);
printf ( "%d\n" ,centereddecagonalnum(n));
return 0;
}
|
Java
import java.io.*;
class GFG
{
static int centereddecagonalnum( int n)
{
return ( 5 * n * n + 5 * n + 1 );
}
public static void main (String[] args)
{
int n = 5 ;
System.out.print(n + "th centered " +
"decagonal number: " );
System.out.println(centereddecagonalnum(n));
n = 9 ;
System.out.print(n + "th centered " +
"decagonal number: " );
System.out.println(centereddecagonalnum(n));
}
}
|
Python3
def centereddecagonalnum(n) :
return ( 5 * n * n +
5 * n + 1 )
if __name__ = = '__main__' :
n = 5
print (n, "th centered decagonal " +
"number : " ,
centereddecagonalnum(n))
n = 9
print (n, "th centered decagonal " +
"number : " ,
centereddecagonalnum(n))
|
C#
using System;
class GFG
{
static int centereddecagonalnum( int n)
{
return (5 * n * n + 5 * n + 1);
}
static public void Main ()
{
int n = 5;
Console.Write(n + "th centered decagonal" +
"number: " );
Console.WriteLine(centereddecagonalnum(n));
n = 9;
Console.Write(n + "th centered decagonal" +
"number: " );
Console.WriteLine(centereddecagonalnum(n));
}
}
|
PHP
<?php
function centereddecagonalnum( $n )
{
return (5 * $n * $n +
5 * $n + 1);
}
$n = 5;
echo $n , "th centered decagonal" ,
"number: " ;
echo centereddecagonalnum( $n );
echo "\n" ;
$n = 9;
echo $n , "th centered decagonal" ,
"number: " ;
echo centereddecagonalnum( $n );
?>
|
Javascript
<script>
function centereddecagonalnum(n)
{
return (5 * n * n + 5 * n + 1);
}
var n = 5;
document.write(n + "th centered " +
"decagonal number: " );
document.write(centereddecagonalnum(n) + "<br>" );
n = 9;
document.write(n + "th centered " +
"decagonal number: " );
document.write(centereddecagonalnum(n));
</script>
|
Output
5th centered decagonalnumber: 151
9th centered decagonalnumber: 451
Time Complexity: O(1)
Auxiliary Space: O(1)
Last Updated :
19 May, 2022
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