Given integers $a,b,c$ such that $\gcd(a,b,c) = 1$, it is well known that there exists only a finite set of numbers $n$ such that $n$ is not expressible as $ax+by+cz$ for non negative integers $x$,$y$,$z$. 


It is also known that there exists a quadratic time algorithm for finding the maximal such $n$. However I was not able to spot the paper covering the algorithm.


Anybody happens to know the algorithm and/or a (free) reference to it?



Frobenius number for three numbers
Simple algoritm based on continued fractions was proposed by Rödseth, O. J. On a linear Diophantine problem of Frobenius J. Reine Angew. Math., 1978, 301, 171-178


All algorithm are described in Ramrez Alfonsn, J. L. The Diophantine Frobenius problem Oxford University Press, 2005


I think that Mathematica uses Rödseth's algoritm <http://demonstrations.wolfram.com/PositiveFrobeniusNumbersOfThreeArguments/>


