Given a number N, the task is to find the Nth (N may be up to 10^18) term of this series:
2, 10, 24, 44, 70…..
The answer can be very large so print answer under modulo 10^9+9.
Examples:
Input: N = 2 Output: 10 Input: N = 5 Output: 70
Approach:The formula for Nth term will be:
Nth term = 3*n*n – n
Below is the implementation of the above approach:
C++
// CPP program to find // the Nth term of the series// 2, 10, 24, 44, 70.....#include <bits/stdc++.h>using namespace std;#define mod 1000000009// function to return nth term of the seriesint NthTerm(long long n){ long long x = (3 * n * n) % mod; return (x - n + mod) % mod;}// Driver codeint main(){// Get N long long N = 4; // Get Nth term cout << NthTerm(N); return 0;} |
C
// C program to find // the Nth term of the series// 2, 10, 24, 44, 70.....#include <stdio.h>#define mod 1000000009// function to return nth term of the seriesint NthTerm(long long n){ long long x = (3 * n * n) % mod; return (x - n + mod) % mod;}// Driver codeint main(){// Get N long long N = 4; // Get Nth term printf("%d",NthTerm(N)); return 0;}// This code is contributed by kothavvsaakash. |
Java
// Java program to find N-th// term of the series:import java.util.*;import java.lang.*;import java.io.*;class GFG { // function to return nth term of the series static long NthTerm(long n) { long x = (3 * n * n) % 1000000009; return (x - n + 1000000009) % 1000000009; } // Driver Code public static void main(String args[]) { // Taking n as 4 long N = 4; // Printing the nth term System.out.println(NthTerm(N)); }} |
Python3
# Python 3 program to find # N-th term of the series: # Function for calculating # Nth term of series def NthTerm(N) : # return nth term x = (3 * N*N)% 1000000009 return ((x - N + 1000000009)% 1000000009) # Driver code if __name__ == "__main__" : N = 4 # Function Calling print(NthTerm(N)) |
C#
// C# program to find N-th// term of the series:using System;class GFG{// function to return nth // term of the seriesstatic long NthTerm(long n){ long x = (3 * n * n) % 1000000009; return (x - n + 1000000009) % 1000000009;}// Driver Codepublic static void Main(){ // Taking n as 4 long N = 4; // Printing the nth term Console.Write(NthTerm(N));}}// This code is contributed// by ChitraNayal |
PHP
<?php// PHP program to find // the Nth term of the series// 2, 10, 24, 44, 70.....// function to return Nth// term of the seriesfunction NthTerm($n){ $mod = 1000000009; $x = (3 * $n * $n) % $mod; return ($x - $n + $mod) % $mod;}// Driver code$N = 4;// Get Nth termecho NthTerm($N);// This code is contributed // by Mahadev99?> |
Javascript
<script>// Javascript program to find N-th// term of the series: // function to return nth term of the series function NthTerm( n) { let x = (3 * n * n) % 1000000009; return (x - n + 1000000009) % 1000000009; } // Driver Code // Taking n as 4 let N = 4; // Printing the nth term document.write(NthTerm(N));// This code contributed by Princi Singh </script> |
Output:
44
Time Complexity: O(1)
Auxiliary Space: O(1)
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