Pentagonal Number

Calculates the pentagonal number of the given order.

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Interface
Pentagonal Number
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Interface

C++

Excel

Pentagonal Number

intpentagonal_number( int n )[inline]

This function computes the pentagonal number of order n. The pentagonal number $\inline P(n)$ counts the number of dots in a figure of $\inline n$ nested pentagons. The pentagonal numbers are defined for both positive and negative orders.

Example:

#include <codecogs/maths/combinatorics/sequences/pentagonal_number.h>
#include <iostream>
int main()
{
  std::cout << "Pentagonal numbers for 0 <= n < 10" << std::endl;
  for (int i = 0; i < 10; i++)
    std::cout << i << "  " << Maths::Combinatorics::Sequences::pentagonal_number(i) << std::endl;
  return 0;
}

Output:

Pentagonal numbers for 0 <= n < 10
0  0
1  1
2  5
3  12
4  22
5  35
6  51
7  70
8  92
9  117

References:

SUBSET, a C++ library of combinatorial routines, http://www.csit.fsu.edu/~burkardt/cpp_src/subset/subset.html

Parameters

n	the desired order

Returns

the value of the pentagonal number of order n

Authors

Lucian Bentea (August 2005)

Source Code

Source code is available when you buy a Commercial licence.

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