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 A114971 #28 Sep 08 2022 08:45:23 %S A114971 1,4,8,14,16,22,23,32,34,50,52,62,80,154,170,176,202,208,214,236,248, %T A114971 332,398,422 %N A114971 Numbers n such that 3^n + n^3 is a semiprime. %C A114971 a(25) >= 428. - _Hugo Pfoertner_, Jul 28 2019 %H A114971 <a href="http://factordb.com/index.php?query=3%5E428%2B428%5E3">Status of 3^428-428^3 in factordb.com</a>. %e A114971 4 is OK because 3^4 + 4^3 = 81 + 64 = 145 = 5*29 (semiprime). %t A114971 Select[Range[100], PrimeOmega[3^# + #^3]==2&] (* _Vincenzo Librandi_, May 21 2014 *) %o A114971 (Magma)IsSemiprime:=func< n | &+[ k[2]: k in Factorization(n) ] eq 2 >; [ n: n in [1..95] | IsSemiprime(3^n+n^3)]; // _Vincenzo Librandi_ Dec 16 2010 %Y A114971 Cf. A114970, A114973, A114974. %K A114971 nonn,more,hard %O A114971 1,2 %A A114971 _Zak Seidov_, Feb 22 2006 %E A114971 a(14)-a(23) from _Luke March_, Jul 27 2015 %E A114971 a(24) from _Hugo Pfoertner_, Jul 28 2019