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 A054821 #7 Nov 21 2013 12:47:23
%S A054821 23,47,89,113,233,293,317,353,359,389,409,449,467,509,577,647,683,691,
%T A054821 839,863,887,919,1039,1069,1097,1201,1237,1283,1307,1327,1381,1433,
%U A054821 1439,1459,1493,1499,1559,1613,1627,1637,1709,1889,2003,2039,2099,2179
%N A054821 Third term of weak prime quartet: p(m-1)-p(m-2) < p(m)-p(m-1) < p(m+1)-p(m).
%t A054821 wpqQ[listn_]:=Module[{d=Differences[listn]},d[[1]]<d[[2]]&& d[[2]]<d[[3]]]; Transpose[Select[Partition[Prime[Range[500]],4,1], wpqQ]] [[3]] (* _Harvey P. Dale_, Apr 11 2011 *)
%Y A054821 Cf. A051635, A054800-A054840.
%K A054821 nonn
%O A054821 1,1
%A A054821 _Henry Bottomley_, Apr 10 2000