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 A303008 #7 Apr 24 2018 12:10:08 %S A303008 2,126217792286,600030498926,1248599869826,226537279412126, %T A303008 7615111129051346,9609149773927166,17502271515299726, %U A303008 20140666152370226,126921319513852046,133564589570047406,141572739574418846,185615640867777506,193420934175277166 %N A303008 Even pseudoprimes m (A006935) such that 2m+1 is prime. %C A303008 For n>1, 2*a(n)+1 belongs to A300193. %Y A303008 Subsequence of A006935. %Y A303008 Cf. A300193, A303009, A303447, A303448. %K A303008 nonn,hard %O A303008 1,1 %A A303008 _Max Alekseyev_, Apr 17 2018