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 A140784 #4 Mar 30 2012 17:39:37 %S A140784 14,55,35,6,46,15,26,437,146,237,95,1082,818,597,1603,2705,2078,4511, %T A140784 1418,2681,14545,13863,37551,6559,16053,55805,26707,17965,308918, %U A140784 32777,41222,35103,393565,219509,153263,87627,2263057,35981,1789339,741841 %N A140784 a(n) = least member of A006881 whose difference from the following one equals n, or 0 if no such semiprime exists. %e A140784 If psd(j) = A006881(j), psd(1)=6 and psd(2)=10, hence a(4)=6; psd(3) =14 and psd(4)=15, hence a(1)=14 %Y A140784 Cf. A001358, A006881, A131109. %K A140784 nonn %O A140784 1,1 %A A140784 Philippe Lallouet (philip.lallouet(AT)orange.fr), Jul 13 2008 %E A140784 Edited by _N. J. A. Sloane_, Jul 20 2008 %E A140784 Corrected a(21), a(22), a(36), extended by _R. J. Mathar_, Jul 23 2008