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 A088502 #15 Sep 08 2022 08:45:11 %S A088502 5,7,9,11,13,17,19,21,23,27,31,33,39,41,43,49,53,57,61,63,71,77,79,83, %T A088502 89,91,93,97,101,107,109,111,113,119,121,129,131,133,137,141,153,167, %U A088502 171,173,179,187,189,193,201,203,207,229,231,241,251,253,261,263,269 %N A088502 Numbers n such that (n^2 - 5)/4 is prime. %C A088502 Under Bunyakovsky's conjecture this sequence is infinite. - _Charles R Greathouse IV_, Dec 28 2011 %H A088502 Vincenzo Librandi, <a href="/A088502/b088502.txt">Table of n, a(n) for n = 1..1000</a> %F A088502 a(n) = 2*A002328(n) - 1 = Sqrt(A110013(n)). - _Ray Chandler_, Sep 07 2005 %e A088502 (23*23 - 5)/4 = 131, 131 is prime, 23 is the 9th n of the sequence. %t A088502 Select[Range[500], PrimeQ[(#^2 - 5)/4] &] (* _Vincenzo Librandi_, Oct 06 2012 *) %o A088502 (PARI) for(k=2,1e3,if(isprime(k^2+k-1),print1(2*k+1", "))) \\ _Charles R Greathouse IV_, Dec 28 2011 %o A088502 (Magma) [n: n in [1..300 by 2] | IsPrime((n^2-5) div 4)]; // _Vincenzo Librandi_, Oct 06 2012 %Y A088502 Cf. A002327, A002328, A110013. %K A088502 easy,nonn %O A088502 1,1 %A A088502 _Pierre CAMI_, Nov 13 2003