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 A114974 #28 Sep 08 2022 08:45:23 %S A114974 2,12,16,18,30,39,160,214,235,408 %N A114974 Numbers n such that 7^n + n^7 is a semiprime. %C A114974 627 and 748 are sequence terms < 1100. a(11) >= 510. Unknown factorization also for 622 and 790. - _Hugo Pfoertner_, Jul 28 2019 %H A114974 <a href="http://factordb.com/index.php?query=7%5E510%2B510%5E7">Status of 7^510-510^7 in factordb.com</a>. %e A114974 2 is in the sequence because 7^2 + 2^7 = 177 = 3*59 (semiprime). %e A114974 12 is in the sequence because 7^12 + 12^7 = 13*1067470693 (semiprime). [_Vincenzo Librandi_, Dec 16 2010] %o A114974 (Magma)IsSemiprime:=func<n | &+[k[2]: k in Factorization(n)] eq 2>; [n: n in [1..85] | IsSemiprime(7^n+n^7)] // _Vincenzo Librandi_, Dec 16 2010 %Y A114974 Cf. A114970, A114971, A114973. %K A114974 nonn,more,hard %O A114974 1,1 %A A114974 _Zak Seidov_, Feb 22 2006 %E A114974 Corrected (inserted 12) from _Vincenzo Librandi_, Dec 16 2010 %E A114974 a(7) from _D. S. McNeil_, Dec 16 2010 %E A114974 a(8)-a(10) from _Luke March_, Aug 03 2015