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 A124415 #17 Jan 19 2025 14:18:09
%S A124415 8325,82950,884220,1120470,3441690,5627895,5765505,7664745,7757430,
%T A124415 8555040,10739505,11891625,15514860,15623475,18268455,22631970,
%U A124415 24833775,27373410,29342895,31286970,31577205,50077455,51541035,58646520
%N A124415 Numbers k such that 2*k+1, 4*k+1, 8*k+1, 16*k+1, 32*k+1, 64*k+1 and 128*k+1 are primes.
%H A124415 Amiram Eldar, <a href="/A124415/b124415.txt">Table of n, a(n) for n = 1..1000</a>
%t A124415 Select[15*Range[4000000], And @@ PrimeQ /@ ({2, 4, 8, 16, 32, 64, 128}*# + 1) &] (* _Ray Chandler_, Nov 21 2006 *)
%t A124415 Select[Range[15,59*10^6,15],AllTrue[2^Range[7] #+1,PrimeQ]&] (* _Harvey P. Dale_, Jan 19 2025 *)
%Y A124415 Cf. A005097, A123998, A124041, A124412-A124417.
%K A124415 nonn
%O A124415 1,1
%A A124415 _Artur Jasinski_, Nov 02 2006
%E A124415 Corrected and extended by _Ray Chandler_, Nov 21 2006