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 A161143 #7 Dec 04 2017 18:58:10 %S A161143 1,5,25,55,125,275,555,625,1375,2775,3025,3125,5555,6875,13875,15125, %T A161143 15625,27775,30525,34375,55555,69375,75625,78125,138875,152625,166375, %U A161143 171875,277775,305525,308025,346875,378125,390625,555555,694375,763125 %N A161143 Numbers which can be expressed as the product of numbers made of only fives. %e A161143 1 = the empty product; %e A161143 5 = 5; %e A161143 125 = 5 * 5 * 5; 275 = 5 * 55; 2775 = 5 * 555. %Y A161143 Cf. A084034, A161140, A161141, A161142, A161144, A161145, A161146, A161147. %K A161143 nonn,base %O A161143 1,2 %A A161143 _Claudio Meller_, Jun 03 2009, Jun 06 2009 %E A161143 1 added by _N. J. A. Sloane_, Dec 04 2017