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 A109558 #5 Jun 03 2025 01:08:28
%S A109558 7,13,19,47,53,61,73,83,131,359,389,401,449,479,491,691,709,787,811,
%T A109558 829,919,1021,1039,1051,1153,1171,1249,1399,1471,1627,1699,1723,1801,
%U A109558 1879,2017,2029,2053,2069,2089,2099,2143,2297,2399,2447,2579,2621
%N A109558 prime(k) for those k where floor((2*(prime(k+1)-prime(k))*PrimePi(k) mod (8*k))/k) = m with m = 4.
%t A109558 a = Flatten[Table[If[Floor[2*Mod[(Prime[n + 1] - Prime[n])*PrimePi[n]/n, 8]] == 4, Prime[n], {}], {n, 1, 400}]]
%Y A109558 Cf. A000040, A000720, A001359.
%Y A109558 Cf. A109556-A109569 for m = 2..15.
%K A109558 nonn,less
%O A109558 1,1
%A A109558 _Roger L. Bagula_, Jun 27 2005
%E A109558 Name edited and offset corrected by _Amiram Eldar_, Jun 02 2025