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 A333021 #9 Mar 06 2020 00:57:26 %S A333021 2,4,6,16,18,40,42,52,54,78,100,102,104,106,126,160,162,220,222,342, %T A333021 378,438,460,462,498,500,502,856,858,880,882,1086,1276,1278,1300,1422, %U A333021 1480,1482,1566,1660,1662,1804,1806,1996,2058,2200,2202,2236,2238,3016,3018 %N A333021 Starts of runs of 4 consecutive even numbers that are all totient numbers (A002202). %H A333021 Amiram Eldar, <a href="/A333021/b333021.txt">Table of n, a(n) for n = 1..10000</a> %H A333021 Wikipedia, <a href="https://en.wikipedia.org/wiki/Euler%27s_totient_function#Totient_numbers">Totient numbers</a>. %e A333021 2 is a term since 2, 4, 6 and 8 are all totient numbers. %o A333021 (PARI) m = 4; v = vector(m); for(k=1, m, v[k] = istotient(2*k)); for(k = m+1, 1500, if(Set(v) == [1], print1(2*(k-m),", ")); v = concat(v[2..m], istotient(2*k))) %Y A333021 Cf. A000010, A002202, A005277, A063512, A083533, A333019, A333020, A333022, A333023, A333024. %K A333021 nonn %O A333021 1,1 %A A333021 _Amiram Eldar_, Mar 05 2020