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 A067578 #11 Jan 09 2021 10:40:51
%S A067578 1,2,5,12,52,120,752,3200,19968,84480,863232,3637248,44384256,
%T A067578 275152896,2254307328,18459131904,298743496704,1846819160064,
%U A067578 33568893960192,274421835104256,3340027488632832,33963860494909440,752840786973818880,6146715129678397440,123926213264670720000
%N A067578 a(n) = Product_{i=1..n} phi(i) * Sum_{i=1..n} 1/phi(i) where phi is the Euler totient function A000010(n).
%o A067578 (PARI) a(n) = prod(i=1, n, eulerphi(i)) * sum(i=1, n, 1/eulerphi(i)); \\ _Michel Marcus_, Jan 09 2021
%Y A067578 Cf. A000010, A001088, A028415, A048049.
%K A067578 nonn
%O A067578 1,2
%A A067578 _Benoit Cloitre_, Jan 30 2002
%E A067578 More terms from _Michel Marcus_, Jan 09 2021