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 A032617 #13 Jul 28 2021 04:19:48 %S A032617 1,7,9,27,37,45,49,51,55,61,69,75,105,109,115,117,121,151,159,181,187, %T A032617 195,201,211,217,225,247,271,277,285,289,291,301,309,319,321,331,337, %U A032617 339,357,361,367,381,391,399,405,417,421,427,429,435,439 %N A032617 Numbers k such that k concatenated with k+2 is a prime. %H A032617 Robert Israel, <a href="/A032617/b032617.txt">Table of n, a(n) for n = 1..10000</a> %p A032617 filter:= n -> isprime(n*(10^(1+ilog10(n+2))+1)+2): %p A032617 select(filter, [seq(i,i=1..1000,2)]); # _Robert Israel_, Nov 14 2019 %Y A032617 Cf. A032607. %K A032617 nonn,base %O A032617 1,2 %A A032617 _Patrick De Geest_, May 15 1998