Source: /cirosantilli/_file/gmp/antihydra.c

= gmp/antihydra.c
{file}
{tag=GMP example}

Also posted at:
* https://wiki.bbchallenge.org/wiki/Antihydra
* https://cstheory.stackexchange.com/questions/20978/what-is-the-smallest-turing-machine-where-it-is-unknown-if-it-halts-or-not/53326\#53326
* https://cs.stackexchange.com/questions/59344/what-are-very-short-programs-with-unknown-halting-status/162108\#162108