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 P: 211 I've done a power series solution to a differential equation and got the recursive formula for the coefficients below. Now I am to evaluate it for large j and I don't get the answer in the book. I'm not sure what method they are using to get the answer although their answer makes sense physically. a j+1 = aj * 2 * {(j + L + 1) - k }/ ( {j+1}(j + 2L + 2) ) where L and k are constants and j is just an integer index number. If I consider large j I would say aj+1 approx. aj * 2 (j) / ( j * j) = aj * 2/j If I say j => infinity and use l'Hopital's rule I get aj+1 = aj * 2 / (2j + 2L + 3) approx. aj * 1/j The book gets aj+1 approx. aj * 2j / ( j*(j+1)) What rules are they applying to get this? (of course a j+1 means aj+1 and aj means aj )