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 A107481 #10 Apr 01 2020 22:18:14 %S A107481 1,2,3,4,7,11,19,38 %N A107481 Number of different prime factors of the smallest n-perfect number. %H A107481 Achim Flammenkamp, <a href="http://wwwhomes.uni-bielefeld.de/achim/mpn.html">The Multiply Perfect Numbers Page</a>. %F A107481 a(n) = A001221(A007539(n)). %e A107481 a(4)=4 because the smallest 4-perfect number factorization is 2^5*3^3*5*7, which has 4 different prime factors. %Y A107481 Cf. A001221, A007539, A107482. %K A107481 nonn,hard,more %O A107481 1,2 %A A107481 Jose Brox (tautocrona(AT)terra.es), May 27 2005