n = int(input("Enter a number to find its sum! "))
sum = int((n*(n+1)) / 2)
print(str(sum))
main()
Explanation:
Here is some code I quickly came up with, you can rehash it for your liking.
I basically took this formula and translated it into python code on line 3. Make sure you use paratheses correctly when translating forumlas or any equation, Order of Operations is everything.