[math-fun] promic numbers or pronic numbers?

Numbers of the form n(n+1), where n is a positive integer are sometimes called "pronic numbers". See: http://en.wikipedia.org/wiki/Pronic_number However, in Sloane's OEIS both Richard Guy and Michael Somos say this is incorrect and it should be "promic numbers". See http://www.research.att.com/~njas/sequences/?q=2%2C6%2C12%2C20%2C30&sort=0&f... I can't find either in any of my dictionaries. Which is correct? And what are the roots? Jim