3^2 = 9 = 4+5
5^2 = 25 = 12+13
work:
If you want to write an odd number as the sum of two consecutive integers, just subtract 1 then divide by 2 and you'll get the first integer.
Like with 25: first subtract 1 and get 24. Then divide by 2 and get 12. So the integers are 12 and 13.