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 A050679 #21 Oct 01 2023 07:25:40 %S A050679 2,3,4,6,7,11 %N A050679 Positions of 2's in A048288. %H A050679 Patrick De Geest, <a href="http://www.worldofnumbers.com/revfact.htm">Reversed Smarandache Concatenated Numbers, Prime factors from n down to 1</a> %H A050679 M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/michafleuren.htm">Factors and primes of Smarandache sequences</a>. %H A050679 M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/micha.txt">Smarandache Factors and Reverse factors</a> %H A050679 Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_008.htm">Puzzle 8. Primes by Listing</a>, The Prime Puzzles & Problems connection. %t A050679 Select[Range[2,12],PrimeOmega[FromDigits[Flatten[IntegerDigits[Range[#,1,-1]]]]]==2 &] (* _Jayanta Basu_, May 30 2013 *) %Y A050679 Cf. A000422, A046461, A048288, A050680, A050681, A050682. %K A050679 nonn,base,hard,more %O A050679 1,1 %A A050679 _Patrick De Geest_, Aug 15 1999 %E A050679 Offset changed to 1 by _Jinyuan Wang_, Sep 04 2021