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 A052100 #18 Jan 01 2017 17:17:06
%S A052100 0,2,6,4,20,12,42,8,18,60,110,24,156,168,840,16,272,36,342,120,252,
%T A052100 660,506,48,100,1092,54,336,812,1320,930,32,8580,2448,9240,72,1332,
%U A052100 3420,1560,240,1640,420,1806,1320,2520,6072,2162,96,294,300,31008,2184,2756
%N A052100 a(n) = lcm(n, phi(n), n - phi(n)).
%C A052100 If n is a power of a prime p, then a(n) = n*(p-1). - _Robert Israel_, May 20 2015
%H A052100 Ivan Neretin, <a href="/A052100/b052100.txt">Table of n, a(n) for n = 1..10000</a>
%F A052100 a(n) = lcm(n, A000010(n), A051953(n)).
%F A052100 For n=p prime, phi(p)=p-1, cototient(p)=p-1, a(p)=p(p-1)=A009262(p).
%F A052100 a(n) = n*A000010(n)*A051953(n)/A009195(n)^2. - _Robert Israel_, May 20 2015
%e A052100 For n=72, phi(72)=24, cototient(72)=48, a(72) = lcm(72,24,48) = 144.
%e A052100 For n=255, phi(255)=128, cototient(255)=127, a(255) = lcm(255,128,127) = 4145280.
%p A052100 seq(ilcm(n, numtheory:-phi(n),n - numtheory:-phi(n)), n=1..100); # _Robert Israel_, May 20 2015
%t A052100 Table[LCM[n, EulerPhi[n], n - EulerPhi[n]], {n, 53}] (* _Ivan Neretin_, May 20 2015 *)
%Y A052100 Cf. A000010, A051953, A009262.
%K A052100 nonn
%O A052100 1,2
%A A052100 _Labos Elemer_, Jan 20 2000