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 A287842 #19 Dec 23 2024 14:53:45
%S A287842 5,17,97,257,65537
%N A287842 Primes of the form (1 + x)^(2^y) + x^(2^y) where x is a divisor of y.
%H A287842 Juri-Stepan Gerasimov, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/pipermail/seqfan/2014-August/028149.html">x^(y + 1) - y^x</a>, SeqFan list, Aug 18 2014.
%H A287842 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FermatPrime.html">Fermat Prime</a>.
%e A287842 97 is in this sequence because (1 + 2)^(2^2) + 2^(2^2) = 97 is prime and 2 is a divisor of 2.
%t A287842 Sort@ Flatten@ Table[Function[{x, y}, Select[(1 + x)^(2^y) + x^(2^y), PrimeQ]] @@ {Divisors@ #, #} &@ n, {n, 12}] (* _Michael De Vlieger_, Jun 01 2017 *)
%Y A287842 Subsequence of A285886.
%Y A287842 Cf. A019434.
%K A287842 nonn,more
%O A287842 1,1
%A A287842 _Juri-Stepan Gerasimov_, Jun 01 2017