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 A124416 #15 Mar 25 2020 06:50:48
%S A124416 7757430,31286970,360821505,365536215,414779430,418803000,428547690,
%T A124416 428823900,434768475,508654155,584808795,732681630,809814510,
%U A124416 846079035,857095380,968314215,1115279880,1187901285,1193371860,1244805450
%N A124416 Numbers k such that 2*k+1, 4*k+1, 8*k+1, 16*k+1, 32*k+1, 64*k+1, 128*k+1 and 256*k+1 are primes.
%H A124416 Amiram Eldar, <a href="/A124416/b124416.txt">Table of n, a(n) for n = 1..100</a>
%t A124416 Select[15*Range[10^8], And @@ PrimeQ /@ ({2, 4, 8, 16, 32, 64, 128, 256}*# + 1) &] (* _Ray Chandler_, Nov 21 2006 *)
%t A124416 Select[15*Range[83*10^6],AllTrue[#*2^Range[8]+1,PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Feb 23 2020 *)
%Y A124416 Cf. A005097, A123998, A124041, A124412-A124417.
%K A124416 nonn
%O A124416 1,1
%A A124416 _Artur Jasinski_, Nov 02 2006
%E A124416 Extended by _Ray Chandler_, Nov 21 2006