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 A217195 #11 Sep 29 2012 18:18:22 %S A217195 17,37,41,53,67,71,79,89,97,113,131,157,163,211,223,239,251,269,293, %T A217195 307,311,331,337,367,373,379,397,409,419,439,449,487,491,499,521,547, %U A217195 593,599,613,631,673,683,691,701,709,733,739,751,757,769,773,787,809 %N A217195 Primes p such that p-2 is the greatest semiprime less than p. %C A217195 This is a subsequence of A063638. %H A217195 T. D. Noe, <a href="/A217195/b217195.txt">Table of n, a(n) for n = 1..1000</a> %e A217195 487 is prime, 486 = 2*3^5 is not semiprime and 485 = 5*97 is semiprime. %t A217195 SemiPrimeQ[n_Integer] := If[Abs[n] < 2, False, (2 == Plus @@ Transpose[FactorInteger[Abs[n]]][[2]])]; Select[Prime[Range[200]], ! SemiPrimeQ[# - 1] && SemiPrimeQ[# - 2] &] (* _T. D. Noe_, Sep 27 2012 *) %o A217195 (PARI) forprime(p=3, 9999, bigomega(p-2)==2 && bigomega(p-1)!=2 & print1(p", ")) %K A217195 nonn %O A217195 1,1 %A A217195 _Antonio Roldán_, Sep 27 2012