The conjunction of two broods of cicadas is going on now. It is called a super-brood. One brood has a 13 year cycle, and the other brood has a 17 year cycle. Using maxima, one can calculate the number of years for this conjunction with the least common multiple function.
(%i1) load("functs");
(%o1) /usr/share/maxima/5.41.0/share/simplification/functs.mac
(%i2) lcm(13,17);
(%o2) 221
The combined cycle is 221 years! This last happened in 1803.
(%i3) 2024-221;
(%o3) 1803
