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. The n-th decagonal number is given by the formula D(n)=4n2-3n;
The first few decagonal numbers are:
0, 1, 10, 27, 52, 85, 126, 175, 232, 297, 370, 451, 540, 637, 742, 855, 976, 1105, 1242……
Input : n = 2 Output : 10 Input : n = 5 Output : 85 Input : n = 7 Output: 175
Decagonal Number is = 370
References : Mathworld
This article is contributed by DANISH_RAZA. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to firstname.lastname@example.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
- Centered decagonal number
- Decagonal Numbers
- Program to find the next prime number
- Program to find the number of men initially
- Program to find the Nth number of the series 2, 10, 24, 44, 70.....
- Program to find the number from given holes
- Program to find the Hidden Number
- Program to find the Nth Harmonic Number
- Program to find Cullen Number
- Program to find the nth Kynea number
- Program to find Nth odd Fibonacci Number
- Program to find the Nth Prime Number
- Program to find Star number
- Program to find number of squares in a chessboard
- Program to find last two digits of Nth Fibonacci number