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 A089432 #4 Mar 30 2012 18:50:42 %S A089432 3,7,15,19,23,27,35,39,47,55,67,75,95,99,107,119,127,135,163,179,187, %T A089432 195,227,235,239,243,255,267,303,319,327,347,379,407,427,443,455,459, %U A089432 463,479,523,539,547,555,583,607,619,635,663,667,683,687,695,715,723 %N A089432 Numbers n such that n concatenated with floor(n/2) is prime. %C A089432 All terms are odd. %Y A089432 Cf. A054211. %K A089432 nonn,base %O A089432 1,1 %A A089432 _Reinhard Zumkeller_, Dec 28 2003