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 A122040 #16 Oct 11 2019 14:08:24
%S A122040 12,15,22,26,30,34,38,42,55,64,77,82,87,92,101,105,110,115,126,139,
%T A122040 144,160,165,170,190,227,232,274,279,292,298,304,312,326,339,346,352,
%U A122040 358,369,375,387,393,406,413,419,431,436,442,447,452,469,481,516,524,533
%N A122040 Numbers which are equal to the arithmetic mean of six successive primes.
%e A122040 a(1) = 12 because (5+7+11+13+17+19)/6 = 12;
%e A122040 a(2) = 15 because (7+11+13+17+19+23)/6 = 15.
%t A122040 Select[Table[Sum[Prime[k], {k, n, n + 5}]/6, {n, 100}], IntegerQ] (* _Ray Chandler_, Sep 25 2006 *)
%t A122040 Select[Mean/@Partition[Prime[Range[200]],6,1],IntegerQ] (* _Harvey P. Dale_, Apr 01 2011 *)
%Y A122040 Cf. A122531.
%K A122040 easy,nonn
%O A122040 1,1
%A A122040 _Giovanni Teofilatto_, Sep 14 2006
%E A122040 Extended by _Ray Chandler_, Sep 25 2006