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 A096305 #36 Jul 13 2025 10:59:05
%S A096305 0,1,2,3,5,7,9,14,23,129,198,235,275,630,870,1033,1290,3293,3458,
%T A096305 11466,13885,25893,32186,33139,58125,78929,97197,121933,128422,442674
%N A096305 Numbers k such that 7^k + 4 is prime.
%e A096305 7^14 + 4 = 678223072853 is a prime number.
%t A096305 Do[If[PrimeQ[7^n+4], Print[n]], {n, 1, 1000}]
%o A096305 (PARI) for(n=0, 10^5, if(ispseudoprime(7^n+4), print1(n, ", "))) \\ _Felix Fröhlich_, Jun 04 2014
%Y A096305 Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.
%K A096305 nonn,more
%O A096305 1,3
%A A096305 Herman H. Rosenfeld (herm3(AT)pacbell.net), Jun 26 2004
%E A096305 More terms (probable primes) from _Rick L. Shepherd_, Jun 29 2004
%E A096305 7 more terms from _Jason Earls_, Feb 16 2008
%E A096305 a(25)-a(27) from _Robert Price_, Jan 24 2014
%E A096305 a(28)-a(29) from Lelio R. Paula, Nov 2014
%E A096305 a(30) from _Paul Bourdelais_, Feb 11 2021