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 A280820 #8 Sep 08 2022 08:46:18
%S A280820 1,2,4,7,31,36,756,861,3101,3290,3632090,3632475,482634075,482653380,
%T A280820 483550276,485577301,20923275465301,20923275550386,6423296981278386,
%U A280820 6423296990008107,6423344287544107,6423345537481432,1124007151123145161432,1124007151123182343577
%N A280820 Partial sums of A001783.
%C A280820 A001783(n) = the product of totatives of n.
%F A280820 a(n) = Sum_{i=1..n} A001783(i).
%t A280820 Accumulate@ Table[Times @@ Select[Range@ n, CoprimeQ[n, #] &], {n, 24}] (* _Michael De Vlieger_, Jan 09 2017 *)
%o A280820 (Magma) [&+[&*[h: h in [1..k] | GCD(h,k) eq 1]: k in [1..n]]: n in [1..100]]
%Y A280820 Cf. A001783, A280821.
%K A280820 nonn
%O A280820 1,2
%A A280820 _Jaroslav Krizek_, Jan 08 2017