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 A046463 #16 Oct 16 2019 01:56:06 %S A046463 9,16,23,29,37,38,43,58,59 %N A046463 Numbers k such that the concatenation of numbers from 1 to k is the product of 4 primes (not necessarily distinct). %H A046463 Patrick De Geest, <a href="http://www.worldofnumbers.com/factorlist.htm">Normal Smarandache Concatenated Numbers, Prime factors from 1 up to n</a> %H A046463 M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/michafleuren.htm">Factors and primes of Smarandache sequences</a>. %H A046463 Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_008.htm">Primes by Listing</a>, The Prime Puzzles & Problems Connection. %t A046463 Select[Range[60],PrimeOmega[FromDigits[Flatten[IntegerDigits/@ Range[#]]]] == 4&] (* _Harvey P. Dale_, Jan 15 2013 *) %Y A046463 Cf. A046460. %K A046463 nonn,hard,base %O A046463 1,1 %A A046463 _Patrick De Geest_, Aug 15 1998