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 A075899 #26 Sep 14 2015 14:57:39
%S A075899 13,97,59149,31381060093,12157665459056930401
%N A075899 Primes of the form 3^n + n^2.
%C A075899 The next term (a(6)) has 146 digits; a(7) has 755 digits. - _Harvey P. Dale_, May 21 2013
%H A075899 Charles R Greathouse IV, <a href="/A075899/b075899.txt">Table of n, a(n) for n = 1..7</a>
%t A075899 f[n_]:=3^n+n^2; lst={};Do[If[PrimeQ[f[n]],AppendTo[lst,f[n]]],{n,3*5!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jul 24 2009 *)
%t A075899 Select[Table[3^n+n^2,{n,0,2000}],PrimeQ] (* _Harvey P. Dale_, May 21 2013 *)
%o A075899 (PARI) list(lim)=my(v=List(),t); forstep(n=2,logint(lim\1,3),2, if(ispseudoprime(t=3^n+n^2) && t<=lim, listput(v,t))); Vec(v) \\ _Charles R Greathouse IV_, Sep 14 2015
%o A075899 (PARI) is(n)=my(e=logint(n,3)); e%2==0 && n==3^e+e^2 && isprime(n) \\ _Charles R Greathouse IV_, Sep 14 2015
%Y A075899 Cf. A075898 (for the corresponding n).
%K A075899 nonn
%O A075899 1,1
%A A075899 _Zak Seidov_, Oct 17 2002
%E A075899 a(6) (moved to b-file) from _Vladimir Joseph Stephan Orlovsky_, Jul 24 2009