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 A173421 #15 Sep 08 2022 08:45:50
%S A173421 28,351,1891,4851,7381,9453,15931,26565,31125,68635,90951,110685,
%T A173421 130305,140185,218791,224785,240471,243253,309291,341551,466095,
%U A173421 497503,780625,889111,899811,1122751,1188111,1214461,1269621,1334161,1408681,1595791
%N A173421 Triangular numbers which are sums of 5 consecutive primes.
%H A173421 Chai Wah Wu, <a href="/A173421/b173421.txt">Table of n, a(n) for n = 1..10000</a>
%e A173421 28 = 2 + 3 + 5 + 7 + 11.
%t A173421 f[n_]:=Prime[n]+Prime[n+1]+Prime[n+2]+Prime[n+3]+Prime[n+4]; Select[Table[f[n],{n,9!}],IntegerQ[Sqrt[1+8# ]]&]
%t A173421 Select[Total/@Partition[Prime[Range[50000]],5,1],OddQ[Sqrt[1+8#]]&] (* _Harvey P. Dale_, Feb 08 2020 *)
%o A173421 (Magma) [ t: n in [1..28000] | IsSquare(8*t+1) where t is &+[NthPrime(n+s): s in [0..4]] ]; // _Bruno Berselli_, Apr 28 2011
%Y A173421 Cf. A000040, A000217, A111163, A167788, A173420.
%K A173421 nonn
%O A173421 1,1
%A A173421 _Vladimir Joseph Stephan Orlovsky_, Feb 18 2010