About the pythagorean sets having the smallest number as an odd number-

3,4,5 (last number will be achieved by adding one to second number)

5,12,13(add the sum of two starting mubers of the previous set to starting number i.e. 5+(3+4)=12, so second nuber of this set is 12 and last number we will get by adding 1 in this number i.e. 12+1=13)

same way..........
7 7+(5+12)=24 24+1=25
9 9+(7+24)=40 40+1=41
11 11+(9+40)=60 60+1=61
...so on
remember this is true when the smallest number of the set is an odd number, also there may be other combinations possible taking the smallest number as an odd number for example... 9, 12, 15(but this is the mutiple of set 3,4,5)
any comment please...
and this is my personal observation, if any rule is there let me know...