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 A275489 #7 Jul 29 2016 21:19:03 %S A275489 1,2,4,6,10,13,17,22,30,38,45,53,63,74,83,96,112,128,145 %N A275489 Most consecutive numbers that can be covered with arithmetic progressions of differences 2i+1, 1<=i<=n. %C A275489 Erdos and Selfridge conjecture that there is no covering system whose moduli are distinct odd integers > 1. This is equivalent to saying that a(n) is finite for all n. %H A275489 Wikipedia, <a href="https://en.wikipedia.org/wiki/Covering_system">Covering system</a>. %e A275489 [1,2,3,4] can be covered by the arithmetic progressions 3k+1, 5k+2 and 7k+3 but [1,2,3,4,5] can't be covered by three arithmetic progressions with differences 3, 5 and 7, so a(3) = 4. %K A275489 nonn,more %O A275489 1,2 %A A275489 _Robert Israel_, Jul 29 2016