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 A131208 #11 Jul 11 2015 16:47:06
%S A131208 1,2,1,3,1,5,1,3,1,7,1,1,3,1,11,3,5,13,7,1,5,7,17,7,19,13,7,1,1,11,23,
%T A131208 1,1,17,11,19,29,1,5,1,1,31,13,1,23,1,1,3,1,37,13,1,5,41,7,43,1,13,23,
%U A131208 31,47,13,1,1,17,1,23,53,1,1,3,1,1,11,37,29,59,61,31,7
%N A131208 Greatest prime divisor of all composite numbers between n-th semiprime and next semiprime, or 1 if there are no such composite numbers.
%C A131208 Largest of all prime factors of the numbers between semiprime(n) and semiprime(n+1). Semiprime analog of A052248. a(A070552(n)) = 1. This sequence defines a mapping of semiprimes to primes.
%F A131208 a(n) = MAX{(A001358(n) < k < A001358(n+1), A006530(k))}.
%Y A131208 Cf. A001358, A052248, A070552.
%K A131208 easy,nonn
%O A131208 1,2
%A A131208 _Jonathan Vos Post_, Oct 24 2007
%E A131208 Corrected and extended by _R. J. Mathar_, Jan 15 2008