How to add +1 to a python variable every day?

Question

I have three variables

a = 1

b = 2

c = 3

Every day, I need to add 1 to each variable

a = a + 1 (so a=2)

b = b + 1

c = c + 1

But I need that when tomorrow I run the script, to add 1 unit more:

a = a + 2 (so tomorrow a=3, after 2 days a = 4....)

b = b + 2

c = c + 2

And so on...I need every day to add +1.

Any ideas?