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 A175711 #5 Feb 02 2015 05:23:48 %S A175711 2,3,5,7,11,29,41,43,47,53,59,67,73,97,107,109,113,137,149,151,167, %T A175711 179,191,193,211,227,229,233,241,263,269,277,281,307,311,317,359,373, %U A175711 379,383,389,449,457,487,491,499,521,563,571,577,587,593,607,631,661,677 %N A175711 Primes p such that p-th semiprime=r*k and r>=p>=k. %C A175711 a(1)=2 because 2nd semiprime=3*2 and 3>2=2, a(2)=3 because 3rd semiprime=3*3 and 3=3=3, a(3)=5 because 5th semiprime=7*2 and 7>5>2. %Y A175711 Cf. A084126, A084127. %K A175711 nonn %O A175711 1,1 %A A175711 _Juri-Stepan Gerasimov_, Aug 12 2010