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 A227878 #10 Oct 27 2013 05:01:15 %S A227878 3,19,41,43,71,83,101,109,151,167,199,227,229,257,281,283,311,313,349, %T A227878 383,401,443,461,463,487,503,571,601,617,641,643,677,727,757,829,857, %U A227878 859,881,883,911,937,941,971,1033,1063,1091,1093,1123,1187,1217,1231 %N A227878 Primes occurring twice in A051701. %C A227878 Consider five consecutive primes p1..p5: (p3 is a term of this sequence) iff (p2-p1 > p3-p2 and p5-p4 > p4-p3). %H A227878 Reinhard Zumkeller, <a href="/A227878/b227878.txt">Table of n, a(n) for n = 1..10000</a> %o A227878 (Haskell) %o A227878 a227878 n = a227878_list !! (n-1) %o A227878 a227878_list = f a051701_list where %o A227878 f (p:ps@(_:p':_)) = if p == p' then p : f ps else f ps %K A227878 nonn %O A227878 1,1 %A A227878 _Reinhard Zumkeller_, Oct 25 2013