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 A372881 #15 May 16 2024 08:40:38
%S A372881 1,7,19,44,61,133,127,256,297,427,331,836,469,889,1159,1408,817,2079,
%T A372881 1027,2684,2413,2317,1519,4864,2825,3283,4131,5588,2437,8113,2791,
%U A372881 7424,6289,5719,7747,13068,3997,7189,8911,15616,4921,16891,5419,14564,18117,10633,6487,26752
%N A372881 a(n) = Sum_{j=1..n} Sum_{k=1..n} gcd(j*k,n).
%H A372881 Seiichi Manyama, <a href="/A372881/b372881.txt">Table of n, a(n) for n = 1..1000</a>
%o A372881 (PARI) a(n) = sum(j=1, n, sum(k=1, n, gcd(j*k, n)));
%Y A372881 Cf. A018804, A078430.
%K A372881 nonn,mult
%O A372881 1,2
%A A372881 _Seiichi Manyama_, May 15 2024