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 A266676 #8 Jan 03 2016 04:00:32 %S A266676 0,1,4,8,36,14,60,26,84,34,132,46,168,56,180,74,240,82 %N A266676 Smallest span (difference between the start and end) of a symmetric n-tuple of consecutive primes. %C A266676 An n-tuple (p(1),...,p(n)) is symmetric if p(k)+p(n+1-k) is the same for all k=1,2,...,n (cf. A175309). %C A266676 In contrast to A266511, n-tuples here may be singular and give the complete set of residues modulo some prime. For example, for n=3 we have the symmetric 3-tuple: (3,5,7) = (3,3+2,3+4) of span a(3)=4, but there are no other symmetric 3-tuples of the form (p,p+2,p+4), since one of its elements would be divisible by 3. %C A266676 a(n) <= A266511(n). %Y A266676 The smallest starting primes and their indices of the corresponding tuples are given in A266583 and A266585. %Y A266676 Cf. A055380, A065688, A175309, A266511, A266512, A261324. %K A266676 nonn,more %O A266676 1,3 %A A266676 _Max Alekseyev_, Jan 02 2016