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 A071219 #21 Jul 14 2018 09:48:53 %S A071219 2,3,439 %N A071219 Numbers m such that the largest prime factor of prime(m) + prime(m+1) equals m. %C A071219 a(4), if it exists, is larger than 10^7. %C A071219 a(4) > 5*10^14, if it exists. - _Giovanni Resta_, Jul 14 2018 %e A071219 Numbers x such that A006530(A001043(x)) = x. %e A071219 x = 2 is a term: p(2) + p(3) = 3 + 5 = 8 with largest factor = 2 = x. %e A071219 x = 3 is a term: p(3) + p(4) = 5 + 7 = 12 with largest factor = 3 = x. %e A071219 x = 439 is a term: p(439) + p(440) = 3067 + 3079 = 6146 = 2*7*439 = 14x. %t A071219 DeleteCases[#, 0] &@ MapIndexed[Boole[#1 == First@ #2] First@ #2 &, Map[FactorInteger[Total@ #][[-1, 1]] &, Partition[Prime@ Range[10^6], 2, 1]]] (* _Michael De Vlieger_, Aug 09 2017 *) %Y A071219 Cf. A006530, A001043, A071216-A071218. %K A071219 nonn,bref,more %O A071219 1,1 %A A071219 _Labos Elemer_, May 17 2002 %E A071219 Edited by _N. J. A. Sloane_, Aug 09 2017