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 A372906 #10 May 16 2024 10:52:54
%S A372906 1,5,11,21,29,55,55,82,97,145,131,231,181,275,319,312,305,485,379,609,
%T A372906 605,655,551,902,681,905,819,1155,869,1595,991,1184,1441,1525,1595,
%U A372906 2037,1405,1895,1991,2378,1721,3025,1891,2751,2813,2755,2255,3432,2521,3405,3355
%N A372906 a(n) = Sum_{j=1..n} Sum_{k=1..n} gcd(j,n) * gcd(k,n) / gcd(j*k,n).
%H A372906 Seiichi Manyama, <a href="/A372906/b372906.txt">Table of n, a(n) for n = 1..1000</a>
%o A372906 (PARI) a(n) = sum(j=1, n, sum(k=1, n, gcd(j, n)*gcd(k, n)/gcd(j*k, n)));
%Y A372906 Cf. A372881.
%K A372906 nonn,mult
%O A372906 1,2
%A A372906 _Seiichi Manyama_, May 16 2024