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 A173903 #32 Sep 06 2025 15:49:14 %S A173903 2,3,12,15,18,21,27 %N A173903 Numbers k such that both (2^k+1)^2-2 and (2^k-1)^2-2 are prime. %C A173903 a(8) > 9394. - _Max Z. Scialabba_, Jan 21 2024 %C A173903 a(8) > 695631 using A091513 and A091515. - _Michael S. Branicky_, Oct 24 2024 %F A173903 A091513 INTERSECT A091515. - _R. J. Mathar_, Jul 06 2010 %t A173903 Select[Range[3000], PrimeQ[((2^# + 1)^2 - 2)]&&PrimeQ[((2^# - 1)^2 - 2)] &] (* _Vincenzo Librandi_, Aug 21 2014 *) %o A173903 (Magma) [n: n in [1..400] | IsPrime((2^n-1)^2-2) and IsPrime((2^n+1)^2-2)]; %Y A173903 Cf. A091513, A091515. %K A173903 nonn,hard,more,changed %O A173903 1,1 %A A173903 _Vincenzo Librandi_, Mar 08 2010 %E A173903 Definition clarified by _Jon E. Schoenfield_, Jun 18 2010