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++
// Program to find nth // centered decagonal // number #include <bits/stdc++.h> using namespace std;
// Centered decagonal // number function int centereddecagonalnum( int n)
{ // Formula to calculate nth
// centered decagonal number &
// return it into main function.
return (5 * n * n + 5 * n + 1);
} // Driver Code 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
// C Program to find nth // centered decagonal // number #include <stdio.h> // Centered decagonal // number function int centereddecagonalnum( int n)
{ // Formula to calculate nth
// centered decagonal number &
// return it into main function.
return (5 * n * n + 5 * n + 1);
} // Driver Code 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;
} // This code is contributed by kothavvsaakash. |
Java
// Java Program to find nth // centered decagonal number import java.io.*;
class GFG
{ // Centered decagonal
// number function
static int centereddecagonalnum( int n)
{
// Formula to calculate nth
// centered decagonal number &
// return it into main function.
return ( 5 * n * n + 5 * n + 1 );
}
// Driver Code
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));
}
} // This code is contributed by m_kit |
Python3
# Program to find nth # centered decagonal number # Centered decagonal # number function def centereddecagonalnum(n) :
# Formula to calculate
# nth centered decagonal
# number & return it
# into main function.
return ( 5 * n * n +
5 * n + 1 )
# Driver Code if __name__ = = '__main__' :
n = 5
print (n, "th centered decagonal " +
"number : " ,
centereddecagonalnum(n))
n = 9
print (n, "th centered decagonal " +
"number : " ,
centereddecagonalnum(n))
# This code is contributed by m_kit |
C#
// Program to find nth // centered decagonal // number using System;
class GFG
{ // Centered decagonal // number function static int centereddecagonalnum( int n)
{ // Formula to calculate nth
// centered decagonal number &
// return it into main function.
return (5 * n * n + 5 * n + 1);
} // Driver Code 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)); } } // This code is contributed by aj_36 |
PHP
<?php // Program to find nth // centered decagonal number // Centered decagonal // number function function centereddecagonalnum( $n )
{ // Formula to calculate
// nth centered decagonal
// number & return it
// into main function.
return (5 * $n * $n +
5 * $n + 1);
} // Driver Code $n = 5;
echo $n , "th centered decagonal" ,
"number: " ;
echo centereddecagonalnum( $n );
echo "\n" ;
$n = 9;
echo $n , "th centered decagonal" ,
"number: " ;
echo centereddecagonalnum( $n );
// This code is contributed by ajit ?> |
Javascript
<script> // Javascript Program to find nth // centered decagonal number // Centered decagonal // number function function centereddecagonalnum(n)
{ // Formula to calculate nth
// centered decagonal number &
// return it into main function.
return (5 * n * n + 5 * n + 1);
} // Driver Code 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)); // This code is contributed by Kirti </script> |
Output
5th centered decagonalnumber: 151 9th centered decagonalnumber: 451
Time Complexity: O(1)
Auxiliary Space: O(1)