Foro de Filatelia Argentina

15 is a multiple of 3 and 5 !!

5 times 3, 4 and 5 -> 15, 20 and 25


3 times 5, 12 and 13 -> 15, 36, 39

15² = 225 -> 15, 112 and 113 or 15² + 112² = 113²

to be continued ...

16:

16, 30, 34 as a multiple of 8 !

but also

16, 63, 65 as 16² + 63² = 65² or 256 + 3969 = 4225

to be continued ...

17:

17, 144, 145 as 17² + 144² = 145² or 289 + 20736 = 21025

to be continued ...