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 A094180 #14 Apr 01 2021 09:42:35
%S A094180 1,2,3,5,6,7,8,11,12,15,16,17,18,20,21,25,26,27,32,33,35,37,38,41,42,
%T A094180 43,45,48,50,52,53,56,57,58,60,61,63,66,68,70,71,77,78,83,86,87,90,91,
%U A094180 92,95,96,97,100,105,106,108,110,111,116,117,120,121,122,123,125,126,131
%N A094180 Numbers k such that 4*k-1 is divisible only by primes of form 4*m-1 (i.e., by the Gaussian primes A002145).
%H A094180 Amiram Eldar, <a href="/A094180/b094180.txt">Table of n, a(n) for n = 1..10000</a>
%F A094180 a(n) = (A094179(n) + 1)/4. - _Amiram Eldar_, Apr 01 2021
%t A094180 Select[Range[150], AllTrue[FactorInteger[4*# - 1][[;; , 1]], Mod[#1, 4] == 3 &] &] (* _Amiram Eldar_, Apr 01 2021 *)
%o A094180 (PARI) {for(n=1,140,fac=factor(4*n-1);v=vector(matsize(fac)[1],j,fac[j,1])%4;if(vecmin(v)==3,print1(n,",")))} \\ _Klaus Brockhaus_, May 08 2004
%Y A094180 For the actual numbers 4*k-1, see A094179.
%Y A094180 Cf. A002145.
%K A094180 nonn
%O A094180 1,2
%A A094180 _Lekraj Beedassy_, May 06 2004
%E A094180 More terms from _Klaus Brockhaus_, May 08 2004