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 A144231 #14 Jul 14 2019 08:32:55 %S A144231 5,7,11,29,79,83,241,727,6563,19681,59051,4782971,14348909, %T A144231 31381059607,282429536483,2541865828331,150094635296999123, %U A144231 450283905890997361,36472996377170786401,1144561273430837494885949696429 %N A144231 Prime numbers of the form 3^k +- 2 for k >= 1. %C A144231 a(49) = 3^2224 - 2 and a(50) = 3^2521 - 2 are too big for a b-file. - _Robert Israel_, Nov 22 2015 %H A144231 Robert Israel, <a href="/A144231/b144231.txt">Table of n, a(n) for n = 1..48</a> %p A144231 A:= NULL: %p A144231 for k from 1 to 1000 do %p A144231 t:= 3^k; %p A144231 if isprime(t-2) then A:= A, t-2 fi; %p A144231 if isprime(t+2) then A:= A, t+2 fi; %p A144231 od: %p A144231 A; # _Robert Israel_, Nov 22 2015 %t A144231 Reap[For[k = 1, k <= 100, k++, p = 3^k-2; If[PrimeQ[p], Sow[p]]; If[PrimeQ[p+4], Sow[p+4]]]][[2, 1]] (* _Jean-François Alcover_, Dec 18 2013 *) %Y A144231 Cf. A000040, A000668, A014232, A057735. %K A144231 nonn %O A144231 1,1 %A A144231 _Reikku Kulon_, Sep 15 2008