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 A135093 #6 Jul 03 2015 16:07:08 %S A135093 4,6,15,10,21,14,55,33,22,39,26,85,51,34,57,38,115,69,46,203,145,87, %T A135093 58,93,62,259,185,111,74,205,123,82,129,86,235,141,94,371,265,159,106, %U A135093 413,295,177,118,183,122,469,335,201,134,355,213,142,219,146,553,395,237 %N A135093 Least composite number k for each possible difference gpf(k)-lpf(k). %C A135093 Clearly all terms are semiprimes. a(0)=prime(1)^2=4. For n>=1, a(n)=k, a squarefree semiprime, where gpf(k)-lpf(k)=A006530(k)-A020639(k)=A030173(k). %C A135093 For n > 0: first occurrences of A030173(n) in A046665. - _Reinhard Zumkeller_, Jul 03 2015 %H A135093 Reinhard Zumkeller, <a href="/A135093/b135093.txt">Table of n, a(n) for n = 0..10000</a> %e A135093 a(3)=2*5=10 because 5-2=3=A030173(3), where the latter terms are ordered by the increasing possible differences between two distinct primes and no smaller composite number has a difference of 3 between its least and greatest prime factors. %o A135093 (Haskell) %o A135093 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A135093 a135093 0 = 4 %o A135093 a135093 n = (+ 1) $ fromJust $ (`elemIndex` a046665_list) $ a030173 n %o A135093 -- _Reinhard Zumkeller_, Jul 03 2015 %Y A135093 Cf. A001358, A006881, A030173, A020639, A006530. %Y A135093 Cf. A046665. %K A135093 nonn %O A135093 0,1 %A A135093 _Rick L. Shepherd_, Nov 18 2007