From Knuth, the Art of Computer Programming vol. 3 "Sorting and Searching",
p. 318 after describing various methods of sorting files on magtape:

    Goertz's read-forward oscillating sort has the somewhat dubious
    distinction of being one of the first algorithms to be patented as an
    algorithm instead of as a physical device [U.S. Patent 3380029 (April
    23, 1968)]; unless successfully contested, this means it is illegal to
    use the algorithm in a program without permission of the patentee.
    Bencher's read-backwards oscillating sort technique was patented by IBM
    several years later.  [Thus, we have reached the end of the era when
    the joy of discovering a new algorithm was satisfaction enough!  Since
    programming is strongly analogous to the fabrication of a machine, and
    since computer programs are now worth money, patented algorithms are
    inevitable.  Of course the specter of people keeping new techniques
    completely secret is far worse than the public appearance of algorithms
    which are proprietary for a limited time.]

The same section cites patent numbers for various other methods.