An exercise in my Number Theory class.

9.py

import math

square_tri = []

def tri(n):
    return n*(n+1)/2

k = 1
while len(square_tri) < 4:
    val = math.sqrt(tri(k))
    print(int(val))
    print(val)
    if val == int(val):
        square_tri.append(tri(k))

    k += 1

print(square_tri)