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 A219046 #18 Nov 12 2023 13:05:59
%S A219046 1,2,4,5,6,10,14,16,25,50,54,66,76,109,124,129,154,201,210,225,324,
%T A219046 844,1444,2529,3029,3292,3340,9162,44721,45662,114085,197542
%N A219046 Numbers k such that 3^k + 28 is prime.
%C A219046 a(33) > 2*10^5. - _Robert Price_, Nov 12 2013
%e A219046 3^2 + 28 = 37 and 37 is prime, so 2 is a term.
%t A219046 Do[If[PrimeQ[3^n + 28], Print[n]], {n, 10000}]
%o A219046 (PARI) is(n)=isprime(3^n+28) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y A219046 Cf. Sequences of numbers k such that 3^k + m is prime:
%Y A219046 (m = 2) A051783, (m = -2) A014224, (m = 4) A058958, (m = -4) A058959,
%Y A219046 (m = 8) A217136, (m = -8) A217135, (m = 10) A217137, (m = -10) A217347,
%Y A219046 (m = 14) A219035, (m = -14) A219038, (m = 16) A205647, (m = -16) A219039,
%Y A219046 (m = 20) A219040, (m = -20) A219041, (m = 22) A219042, (m = -22) A219043,
%Y A219046 (m = 26) A219044, (m = -26) A219045, (m = 28) A219046, (m = -28) A219047,
%Y A219046 (m = 32) A219048, (m = -32) A219049, (m = 34) A219050, (m = -34) A219051. Note that if m is a multiple of 3, 3^k + m is also a multiple of 3 (for k greater than 0), and as such isn't prime.
%K A219046 nonn,more
%O A219046 1,2
%A A219046 _Nicolas M. Perrault_, Nov 10 2012
%E A219046 a(29)-a(32) from _Robert Price_, Nov 12 2013