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 A266583 #43 Mar 02 2025 23:35:49 %S A266583 2,2,3,5,18713,5,12003179,17,1480028129,13,1542186111157, %T A266583 41280160361347,660287401247633,10421030292115097,3112462738414697093, %U A266583 996689250471604163,258406392900394343851,824871967574850703732309,9425346484752129657862217,824871967574850703732303 %N A266583 Smallest prime starting a symmetric n-tuple of consecutive primes of the smallest span (=A266676(n)). %C A266583 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 A266583 In contrast to A266512, 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), 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 A266583 For any n, a(n) <= n or a(n) = A266512(n). %H A266583 Dmitry Petukhov, Anton Nikonov and Ruslan Vikulov, <a href="https://dxdy.ru/post1668659.html#p1668659">found a(19)</a> and <a href="https://dxdy.ru/post1671408.html#p1671408">proof of that is smallest</a> (in Russian), posts in Symmetric tuples of consecutive primes on dxdy forum. %F A266583 a(n) = A000040(A266585(n)). %Y A266583 Cf. A055380, A065688, A175309, A266511, A266512, A261324. %K A266583 nonn,more %O A266583 1,1 %A A266583 _Max Alekseyev_, Jan 01 2016 %E A266583 a(18)-a(20) added by _Dmitry Petukhov_, Feb 15 2025