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 A173888 #5 Jun 19 2025 21:24:14 %S A173888 0,1,4,5,6,7,8,9,10,17,19,23,25,32,51,55,65,87,129,132,159,171,175, %T A173888 180,242,315,324,358,393,435,467,491,501,507,555,591,680,786,800,1070, %U A173888 1459,1650,1707,2813,2923,3281,4217,5153,6287,6365,6462,10088,10367,14289 %N A173888 Exactly one of (2^n-1)^2-2 and (2^n+1)^2-2 is prime. %C A173888 The numbers which are in A091513 or A091515, but not in both sequences. - _R. J. Mathar_, Mar 09 2010 %e A173888 a(1)=1 because (2^1-1)^2-2=-1 is nonprime and (2^1+1)^2-2=7 is prime. %Y A173888 Cf. A091513, A091515, A091514, A091516. %K A173888 nonn %O A173888 1,3 %A A173888 _Juri-Stepan Gerasimov_, Mar 01 2010 %E A173888 Corrected (0 inserted, 12, 16, 18, 21 removed) and extended by _R. J. Mathar_, Mar 09 2010