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 A159049 #10 Jul 13 2017 22:27:50
%S A159049 5,11,41,71,83,281,383,1181,1601,2351,2633,3491,3833,4283,5783,6221,
%T A159049 6791,8783,10301,10883,11633,12251,14033,15581,18341,26111,26801,
%U A159049 30881,31883,34721,38231,41333,41621,42491,43961,46061,47591,53633,60383
%N A159049 Primes of the form (5+ a triangular number A000217).
%H A159049 Harvey P. Dale, <a href="/A159049/b159049.txt">Table of n, a(n) for n = 1..1000</a>
%e A159049 11 is in the list because it is A000217(3)+5 and a prime. 41=36+5= A000217(8)+5 is a prime. 71=66+5=A000217(11)+5 is a prime.
%t A159049 s=0;lst={};Do[s+=n;p=s+5;If[PrimeQ[p],AppendTo[lst,p]],{n,0,7!}];lst
%t A159049 Select[Accumulate[Range[0,500]]+5,PrimeQ] (* _Harvey P. Dale_, Jul 08 2017 *)
%o A159049 (PARI) for(n=1,500, if(isprime(k=n*(n+1)/2 + 5), print1(k, ", "))) \\ _G. C. Greubel_, Jul 13 2017
%Y A159049 Cf. A055469, A055472, A159047, A159048
%K A159049 nonn,easy
%O A159049 1,1
%A A159049 _Vladimir Joseph Stephan Orlovsky_, Apr 03 2009
%E A159049 Definition rephrased, _R. J. Mathar_, Apr 05 2009