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 A052009 #7 Oct 17 2019 22:37:12 %S A052009 1,10,100,107,109,116,118,146,158,161,164,166,170,178,181,185,187,188, %T A052009 190,229,239,245,254,257,269,275,277,292,293,296,299,329,338,344,356, %U A052009 365,368,383,386,392,407,416,425,434,443,452,455,461,467,469,470,476 %N A052009 Sum of 'n with digits sorted ascending' and 'n with digits sorted descending' is prime. %e A052009 107 is a term because 017 + 710 = 727 is prime. %Y A052009 Cf. A052008. %K A052009 nonn,base %O A052009 0,2 %A A052009 _Patrick De Geest_, Nov 15 1999