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 A220789 #11 Sep 08 2022 08:46:04 %S A220789 3,8,9,10,11,12,15,16,18,19,20,22,23,24,25,26,27,28,32,34,35,36,38,39, %T A220789 40,43,44,48,49,50,51,52,53,55,57,58,60,61,63,65,66,67,68,69,70,72,74, %U A220789 76,77,78,79,82,83,85,86,87,88,89,90,91,92,94,95,96,97,98,99,100 %N A220789 Numbers n such that 2*prime(n)^2 - 1 is not prime. %H A220789 Vincenzo Librandi, <a href="/A220789/b220789.txt">Table of n, a(n) for n = 1..1000</a> %t A220789 Select[Range[200], !PrimeQ[2Prime[#]^2 - 1]&] %o A220789 (Magma) [n: n in [1..220]| not IsPrime(2*NthPrime(n)^2-1)]; %Y A220789 Cf. A092057, A092058. %K A220789 nonn,easy %O A220789 1,1 %A A220789 _Vincenzo Librandi_, Jan 18 2013