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 A273551 #14 Sep 08 2022 08:46:16
%S A273551 257,269,509,65789,4294967549
%N A273551 Primes of the form 2^(2^n) + 253.
%C A273551 Terms given correspond to n = 1, 2, 3, 4, and 5.
%C A273551 Next term >= 2^2^25 + 253. - _Charles R Greathouse IV_, Jun 07 2016
%t A273551 Select[Table[2^(2^n) + 253, {n, 0, 15}], PrimeQ]
%o A273551 (Magma) [a: n in [0..16] | IsPrime(a) where a is 2^(2^n)+253];
%o A273551 (PARI) for(n=1,5, if(ispseudoprime(t=2^2^n+253), print1(t", "))) \\ _Charles R Greathouse IV_, Jun 08 2016
%Y A273551 Cf. similar sequences listed in A273547.
%K A273551 nonn
%O A273551 1,1
%A A273551 _Vincenzo Librandi_, Jun 01 2016