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 A065501 #11 Aug 06 2023 08:18:24 %S A065501 1,3,7,10,9,21,11,30,25,27,15,70,17,33,63,76,21,75,23,90,77,45,27,210, %T A065501 49,51,79,110,33,189,35,168,105,63,99,250,41,69,119,270,45,231,47,150, %U A065501 225,81,51,532,81,147,147,170,57,237,135,330,161,99,63,630,65,105,275,352,153 %N A065501 Number of conjugacy classes in the group SL(2,Z_n) (see A000056). %H A065501 Robin Visser, <a href="/A065501/b065501.txt">Table of n, a(n) for n = 1..500</a> %F A065501 For an odd prime p : a(p) = p + 4. - _Robin Visser_, Aug 06 2023 %o A065501 (Magma) [Nclasses(SpecialLinearGroup(2,ResidueClassRing(n))) : n in [2..50]]; // _Robin Visser_, Aug 06 2023 %Y A065501 Cf. A062354, A000056, A000252 %K A065501 nonn,mult %O A065501 1,2 %A A065501 Dan Fux (dan.fux(AT)OpenGaia.com or danfux(AT)OpenGaia.com), Nov 25 2001 %E A065501 a(23) corrected and more terms from _Robin Visser_, Aug 06 2023