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 A196938 #14 May 20 2013 18:56:59
%S A196938 17,29,67,71,89,97,101,131,163,167,173,191,193,197,211,233,241,257,
%T A196938 263,269,283,307,313,317,337,347,373,419,433,443,449,457,461,463,467,
%U A196938 479,491,503,509,521,523,547,577,599,601,607,617,619,631,641,643,677,683
%N A196938 a(n) is the prime number that is the center element (3rd) of a 5-terms arithmetic progression prime chain.
%C A196938 The Mathematica program gives the first 53 terms.
%C A196938 The Mathematica program is also good for finding sequences with any odd number of terms.
%H A196938 Lei Zhou, <a href="/A196938/b196938.txt">Table of n, a(n) for n = 1..10000</a>
%e A196938 {5,13,[17],23,29} is a 5-term arithmetic progression prime chain, so a(1)=17; (for all primes smaller than 17, no such chains exist)
%e A196938 {5,17,[29].41,53} is a 5-term arithmetic progression prime chain, so a(2)=29; (for all primes in between 17 and 29, no such chains exist)
%t A196938 terms = 5; max=53; i = 1; step = (terms - 1)/2; Table[While[i++; p = Prime[i]; found = 0; j = 0; While[j++; df = 6*j; (p > (step*df)) && (found == 0), found = 1; Do[If[(! PrimeQ[p - k*df]) || (! PrimeQ[p + k*df]), found = 0], {k,1, step}]]; found == 0]; p, {ct, 1, max}]
%Y A196938 Cf. A033451.
%K A196938 nonn,easy
%O A196938 1,1
%A A196938 _Lei Zhou_, Oct 07 2011