The Second decagonal numbers series can be represented as
7, 22, 45, 76, 115, 162, 217, 280,,…..
Nth term
Given an integer N. The task is to find the N-th term of the given series.
Examples:
Input: N = 1
Output: 7
Input: N = 4
Output: 76
Approach: The idea is to find the general term for the Second decagonal numbers. Below is the computation of the general term for second decagonal numbers:
1st Term = 1 * (4*1 + 3) = 7
2nd term = 2 * (4*2 + 3) = 22
3rd term = 3 * (4*3 + 3) = 45
4th term = 4 * (4*4 + 3) = 76
.
.
.
Nth term = n * (4 * n + 3)
Therefore, the Nth term of the series is given as
Below is the implementation of above approach:
C++
#include <iostream>
#include <math.h>
using namespace std;
void findNthTerm( int n)
{
cout << n * (4 * n + 3) << endl;
}
int main()
{
int N = 4;
findNthTerm(N);
return 0;
}
|
Java
class GFG{
static void findNthTerm( int n)
{
System.out.println(n * ( 4 * n + 3 ));
}
public static void main(String[] args)
{
int N = 4 ;
findNthTerm(N);
}
}
|
Python3
def findNthTerm(n):
print (n * ( 4 * n + 3 ))
N = 4 ;
findNthTerm(N);
|
C#
using System;
class GFG{
static void findNthTerm( int n)
{
Console.WriteLine(n * (4 * n + 3));
}
public static void Main(String[] args)
{
int N = 4;
findNthTerm(N);
}
}
|
Javascript
<script>
function findNthTerm(n)
{
document.write(n * (4 * n + 3));
}
let N = 4;
findNthTerm(N);
</script>
|
Time Complexity: O(1)
Auxiliary Space: O(1)
Reference: OEIS
Last Updated :
06 Apr, 2021
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