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 A280458 #15 Jul 04 2025 02:30:21
%S A280458 1,1,3,12,120,720,15120,241920,6531840,130636800,7185024000,
%T A280458 172440576000,13450364928000,564915326976000,33894919618560000,
%U A280458 2169274855587840000,295021380359946240000,15931154539437096960000,2724227426243743580160000,217938194099499486412800000
%N A280458 Partial products of A023896.
%F A280458 a(n) = Sum_{i=1..n} A023896(i).
%t A280458 FoldList[#1 #2 &, Table[Ceiling[(n EulerPhi@ n)/2], {n, 20}]] (* _Michael De Vlieger_, Jan 03 2017 *)
%o A280458 (Magma) [&*[&+[h: h in [1..k] | GCD(h,k) eq 1]: k in [1..n]]: n in [1..100]];
%Y A280458 Cf. A023896 (sum of totatives of n), A213544 (partial sums of A023896).
%K A280458 nonn
%O A280458 1,3
%A A280458 _Jaroslav Krizek_, Jan 03 2017