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 A090669 #31 Jul 07 2024 13:20:34
%S A090669 1,2,4,7,8,12,15,28,31,84,98,128,238,302,859,1508,1586,2091,2796,2888,
%T A090669 3924,4815,5636,6596,7090,20176,22176,56386,84050,115515,245608,
%U A090669 259710,274120
%N A090669 Numbers k such that 7^k - 2 is a prime.
%e A090669 7^12 - 2 = 13841287199 a prime number.
%t A090669 Do[ If[ PrimeQ[7^n - 2], Print[n]], {n, 1, 2000}] (* _Robert G. Wilson v_, Dec 22 2003 *)
%o A090669 (PARI) is(n)=isprime(7^n - 2) \\ _Charles R Greathouse IV_, Apr 28 2015
%Y A090669 Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.
%K A090669 nonn,more
%O A090669 1,2
%A A090669 Herman H. Rosenfeld (herm3(AT)pacbell.net), Dec 16 2003
%E A090669 Corrected and extended by _Robert G. Wilson v_ and _Ray Chandler_, Dec 22 2003
%E A090669 Three more terms from _Ryan Propper_, Dec 07 2008
%E A090669 a(28)-a(30) from _Robert Price_, Jan 24 2014
%E A090669 a(31)-a(32) from _Paul Bourdelais_, Jan 29 2021
%E A090669 a(33) from _Paul Bourdelais_, Aug 02 2023