Leibniz, Jakob Bernoulli, and Euler accepted
$\frac{1}{1-(-1)}= 1 - 1 + 1 - 1 +-... = 1/2$
Wallis and Euler accepted
$\frac{1}{1-2}= 1 + 2 + 4 + ... = -1 > 1/0 > 1 $
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