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 A036305 #27 May 18 2022 07:56:10
%S A036305 25,55,121,125,275,605,625,755,1331,1375,1661,3025,3125,3775,5755,
%T A036305 6655,6875,7555,8305,12661,14641,15125,15625,16621,18271,18875,22801,
%U A036305 28775,33275,34375,37775,41525,57755,63305,73205,75625,77555,77755,78125
%N A036305 Composite numbers whose prime factors contain no digits other than 1 and 5.
%C A036305 All terms are a product of at least two terms of A020453. - _David A. Corneth_, Oct 09 2020
%H A036305 David A. Corneth, <a href="/A036305/b036305.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Alois P. Heinz)
%H A036305 <a href="/index/Pri#prime_factors">Index entries for sequences related to prime factors</a>.
%F A036305 Sum_{n>=1} 1/a(n) = Product_{p in A020453} (p/(p - 1)) - Sum_{p in A020453} 1/p - 1 = 0.0873463128... . - _Amiram Eldar_, May 18 2022
%Y A036305 Cf. A003598, A020453, A036302-A036325.
%K A036305 nonn,easy,base
%O A036305 1,1
%A A036305 _Patrick De Geest_, Dec 15 1998