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 A173297 #14 Oct 22 2020 14:07:32
%S A173297 1,4,9,10,11,12,13,14,16,17,19,26,27,28,30,31,33,35,39,44,45,46,48,53,
%T A173297 55,56,57,60,62,64,65,68,69,70,71,75,76,77,78,80,83,85,86,90,93,94,96,
%U A173297 99,100,103,105,110,111,114,115,117,119,120,125,126,130,134,140,143,144
%N A173297 Numbers k such that exactly one of k^2 + k - 1 and k^2 + k + 1 is prime.
%C A173297 Numbers k such that either k-th oblong number-+1 is prime.
%C A173297 Indices k such that A002378(k)+1 or A002378(k)-1 is prime, but not both. -_R. J. Mathar_, Feb 21 2010
%H A173297 Robert Israel, <a href="/A173297/b173297.txt">Table of n, a(n) for n = 1..10000</a>
%p A173297 isA173297 := proc(n) local p,pplus,pmin ; pmin := isprime(n*(1+n)-1) ; pplus := isprime(n*(1+n)+1) ; if pmin <> pplus then return true; else return false; end if; end proc: for n from 1 to 300 do if isA173297(n) then printf("%d,",n) ; end if; end do ; # _R. J. Mathar_, Feb 21 2010
%Y A173297 Cf. A002378, A088485.
%K A173297 nonn,easy
%O A173297 1,2
%A A173297 _Juri-Stepan Gerasimov_, Feb 15 2010
%E A173297 46 and 86 inserted by _R. J. Mathar_, Feb 21 2010
%E A173297 Edited by _Charles R Greathouse IV_, Mar 24 2010