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 A109555 #17 Apr 06 2022 14:59:49
%S A109555 2,809,821,827,857,881,1019,1031,1049,1061,1091,1151,1229,1277,1289,
%T A109555 1301,1319,1427,1451,1481,1487,1607,1619,1667,1697,1721,1787,1871,
%U A109555 1877,1931,1949,1997,2027,2081,2087,2111,2129,2141,2237,2267,2309,2339,2381
%N A109555 prime(k) for those k where floor(2*(((prime(k + 1) - prime(k))*PrimePi(k)) mod (8*k)) / k) = m with m = 0.
%t A109555 a = Flatten[Table[If[Floor[2*Mod[(Prime[n + 1] - Prime[n])*PrimePi[n]/n, 8]] == 0, Prime[n], {}], {n, 1, 400}]]
%Y A109555 Cf. A109556-A109569 for m = 2..15.
%K A109555 nonn,less
%O A109555 1,1
%A A109555 _Roger L. Bagula_, Jun 27 2005
%E A109555 Offset changed and definition amended by _Georg Fischer_, Apr 06 2022