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 A122531 #4 Apr 18 2018 09:28:42
%S A122531 101,139,227,419,431,883,1021,1231,1303,1433,1447,1543,1583,1621,1721,
%T A122531 1993,2243,2251,2351,2531,2539,2591,2693,2707,2713,2753,3359,3461,
%U A122531 3541,3911,4091,4153,4423,4447,5011,5233,5527,5869,6029,6091,6469,6481,6569
%N A122531 Primes equal to arithmetic mean of 6 successive primes; or primes in A122040(n).
%H A122531 Harvey P. Dale, <a href="/A122531/b122531.txt">Table of n, a(n) for n = 1..1000</a>
%t A122531 Select[Table[Sum[Prime[k],{k,n,n+5}],{n,1,1000}]/6,IntegerQ[ #1]&&PrimeQ[ #1]&]
%t A122531 Select[Mean/@Partition[Prime[Range[900]],6,1],PrimeQ] (* _Harvey P. Dale_, Apr 18 2018 *)
%Y A122531 Cf. A122040.
%K A122531 nonn
%O A122531 1,1
%A A122531 _Alexander Adamchuk_, Sep 17 2006