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 A036304 #28 May 18 2022 07:56:00
%S A036304 121,451,1331,1681,4961,14641,18491,45221,48851,54571,68921,125521,
%T A036304 158521,161051,168551,182081,203401,452551,455521,467851,485221,
%U A036304 497431,537361,590851,600281,758131,1380731,1686781,1697851,1743731,1771561
%N A036304 Composite numbers whose prime factors contain no digits other than 1 and 4.
%C A036304 All terms are a product of at least two terms of A020452. - _David A. Corneth_, Oct 09 2020
%H A036304 David A. Corneth, <a href="/A036304/b036304.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Alois P. Heinz)
%H A036304 <a href="/index/Pri#prime_factors">Index entries for sequences related to prime factors</a>.
%F A036304 Sum_{n>=1} 1/a(n) = Product_{p in A020452} (p/(p - 1)) - Sum_{p in A020452} 1/p - 1 = 0.0122909749... . - _Amiram Eldar_, May 18 2022
%e A036304 The composite 4961 = 11^2 * 41 is in the sequence as the digits of its prime factors are either 1 or 4. - _David A. Corneth_, Oct 17 2020
%Y A036304 Cf. A020452, A036302-A036325.
%K A036304 nonn,easy,base
%O A036304 1,1
%A A036304 _Patrick De Geest_, Dec 15 1998