This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A285052 #15 Apr 12 2017 23:45:21 %S A285052 1,4,4,4,4,16,4,4,4,16,4,16,4,16,16,4,4,16,4,16,16,16,4,16,4,16,4,16, %T A285052 4,64,4,4,16,16,16,16,4,16,16,16,4,64,4,16,16,16,4,16,4,16,16,16,4,16, %U A285052 16,16,16,16,4,64,4,16,16,4,16,64,4,16,16,64,4,16,4,16,16,16,16,64,4,16,4,16,4,64,16,16,16,16,4,64,16 %N A285052 Number of idempotent equivalence classes for multiplication in Zn. %C A285052 Consider triples (a,b,c) over Zn where a*b=c. Map each of the three elements to its idempotent under self multiplication, (g^i) * (g^i) = (g^i). Count the distinct triples. %H A285052 Chad Brewbaker, <a href="https://github.com/chadbrewbaker/endoscope">Endoscope: A toolkit for analysis of endofunctions on small sets</a> %F A285052 Conjecture: a(n) = 4^A001221(n). %e A285052 For n=6: [(0,0,0),(0,1,0),(0,4,0),(0,3,0),(1,0,0),(1,1,1),(1,4,4),(1,3,3),(4,0,0),(4,1,4),(4,4,4),(4,3,0),(3,0,0),(3,1,3),(3,4,0),(3,3,3)], so a(6) = 16. %K A285052 nonn %O A285052 1,2 %A A285052 _Chad Brewbaker_, Apr 08 2017