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 A046872 #4 Mar 30 2012 16:48:23 %S A046872 7,47,191,239,307,463,499,701,743,787,853,1087,1123,1301,1487,1553, %T A046872 1567,1823,2309,2621,2843,2903,3083,3203,3319,3323,3359,3373,3541, %U A046872 3583,3557,3617,3659,3671,3727,3769,3863,3947,4217,4327,4373,4391 %N A046872 F-primes. %C A046872 Call the numbers in A008849 F-numbers; then a prime p is called an F-prime if there exists a squarefree F-number q_1*q_2*...*q_r*p with q_1 < q_2 < ... < q_r < p in which the q_i's are primes but not F-primes. %D A046872 I. Kaplansky, The challenges of Fermat, Wallis and Ozanam (and several related challenges): I. Fermat's first challenge, Preprint, 2002. %Y A046872 Cf. A008849. %K A046872 nonn,nice %O A046872 1,1 %A A046872 _N. J. A. Sloane_, Oct 05 2002