Here's the direct quote from the article, as of Feb 16, 2020 (ctrl+f if you don't believe me):
"it’s not too large a mathematical step to considering equations of the form y^2 = x^3 + ax +b where a, b and c are constants."
As you can see, the equation has no c in it.

Here's the direct quote from the article, as of Feb 16, 2020 (ctrl+f if you don't believe me):

"it’s not too large a mathematical step to considering equations of the form y^2 = x^3 + ax +b where a, b and c are constants."

As you can see, the equation has no c in it.