Some info to start with number checkers. Also, i wanna try the Maxima implementations, and eventually develope something nice.
https://oeis.org/ol_source.txt
https://mrob.com/pub/ries/src/ries.c.txt
https://def.fe.up.pt/pipermail/maxima-discuss/2002/002808.html https://def.fe.up.pt/pipermail/maxima-discuss/2002/002809.html (This one corrects some issues of the previous)