You are given a number n, the task is to find the nth Decagonal number. A decagonal number is a figurate number that extends the concept of triangular and square numbers to the decagon (a ten-sided polygon). The nth decagonal numbers counts the number of dots in a pattern of n nested decagons, all sharing a common corner, where the ith decagon in the pattern has sides made of i dots spaced one unit apart from each other.
Input : n = 3 Output : 27 Input : n = 7 Output : 175
The n-th decagonal number is given by the formula
(4n 2 – 3n).
10th decagonal number : 370
- Centered decagonal number
- C program to find Decagonal Number
- Numbers less than N which are product of exactly two distinct prime numbers
- Print N lines of 4 numbers such that every pair among 4 numbers has a GCD K
- Count numbers which can be constructed using two numbers
- Count numbers which are divisible by all the numbers from 2 to 10
- Maximum sum of distinct numbers such that LCM of these numbers is N
- Absolute difference between the Product of Non-Prime numbers and Prime numbers of an Array
- Absolute Difference between the Sum of Non-Prime numbers and Prime numbers of an Array
- Print numbers such that no two consecutive numbers are co-prime and every three consecutive numbers are co-prime
- Add two numbers using ++ and/or --
- Sum of first n even numbers
- Betrothed numbers
- Hailstone Numbers
- Sum of numbers from 1 to N which are divisible by 3 or 4
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to email@example.com. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
Improved By : jit_t