# Isosceles Triangle

An isosceles triangle is a triangle with (at least) two equal sides.

How many isosceles triangle are possible when you are allowed to choose side length from (1,2,3....N).

**Input**:

Input will contain many test cases(<=10). Each on a new line.

Each Test case will give value of N<=10^8

**Output:**

Print number of isosceles triangle possible.

**Sample Input**:

```
```

1

2

3

4

5

**Sample Output:**

```
```

1

3

7

12

19

**Explanation:**For N=2, triangles possible are (1,1,1) ,(2,2,1) (2,2,2)

Jayant Mukherji

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