The sequence 1 1 ∞ 5 6 3 3 3
For those who want to know more, this topic links nicely into A-D-E theory, Dynkin diagrams, and Coxeter groups.https://www.youtube.com/playlist?list=PL-XzhVrXIVeSVcV9iRJ4S...https://www.youtube.com/playlist?list=PL-XzhVrXIVeQ298S6uCyo...http://math.ucr.edu/home/baez/week230.htmlhttps://unapologetic.wordpress.com/category/geometry/root-sy...http://www.math.harvard.edu/~lurie/papers/thesis.pdfBeautiful world this author is peeking into. Enjoy.