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 A175720 #10 Dec 19 2022 11:11:58 %S A175720 1,16,240,17293822569102704640 %N A175720 Duplicate of A173605. %F A175720 A000005(a(n)) = a(n-1) + 4 for n >= 2. %e A175720 a(3) = 240 = the smallest number with 16 + 4 = 20 divisors. %Y A175720 Cf. A014221, A173603, A175719. %K A175720 dead %O A175720 1,2 %A A175720 _Jaroslav Krizek_, Aug 15 2010