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 A211121 #10 Oct 26 2024 19:49:31
%S A211121 3,5,7,9,15,21,25,27,75,135,1575
%N A211121 One of 17 possible sets of eleven numbers of the form 3^alpha 5^beta 7^gamma whose sum of reciprocals is 1.
%H A211121 Nechemia Burshtein, <a href="https://doi.org/10.1016/j.disc.2007.08.049">All the solutions of the equation Sum_{i=1..11} 1/x_i = 1 in distinct integers of the form x_i = 3^alpha 5^beta 7^gamma</a>, Disc. Math. (2008) Vol. 308, No. 18, 4286-4292. MR2427761 (2009e:11061)
%Y A211121 The 17 solutions are given in A201643, A211118-A211132, A211134.
%Y A211121 Cf. A201644, A201646, A201647, A201648, A201649.
%K A211121 nonn,fini,full
%O A211121 1,1
%A A211121 _N. J. A. Sloane_, Apr 02 2012