from fractions import Fraction
from math import isqrt


def gen():
    k = 1
    while 1:
        i = 1
        while i <= k:
            yield (i, k - i + 1)
            i += 1
        k += 1
g = gen()
seen = set()

n = 0
for _ in range(25):
    a, b = next(g)
    f = Fraction(a, b)
    if not f in seen:
        seen.add(f)
        print(f"u{n} = {f}")
        n += 1
    else:
            print("previously seen :", f"{a}/{b} = {f}")