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 A093184 #13 May 30 2019 14:04:38
%S A093184 0,4,76,1120,13428,151342,1642285,17405478,181923798,1883330510,
%T A093184 19364376037,198115964781,2019328569227
%N A093184 Number of consecutive runs of just 1 odd nonprime congruent to 3 mod 4 below 10^n.
%F A093184 Generate the odd nonprime sequence with nonprimes labeled 1 mod 4 or 3 mod 4. Add count of nonprimes to sequence if just 1 nonprime congruent to 3 mod 4 occurs before interruption of a nonprime congruent to 1 mod 4.
%e A093184 a(3)=76 because 76 single nonprime runs occur below 10^3, each run interrupted by a nonprime congruent to 1 mod 4
%t A093184 A091113 = Select[4 Range[0, 10^4] + 1, ! PrimeQ[#] &];
%t A093184 A091236 = Select[4 Range[0, 10^4] + 3, ! PrimeQ[#] &];
%t A093184 lst = {}; Do[If[Length[s = Select[A091236, Between[{A091113[[i]], A091113[[i + 1]]}]]] == 1, AppendTo[lst, s]], {i, Length[A091113] - 1}]; Table[Count[Flatten[lst], x_ /; x < 10^n], {n, 4}] (* _Robert Price_, May 30 2019 *)
%Y A093184 Cf. A093183, A093185, A093186, A093187, A093188, A093397, A093398, A093399, A092637.
%K A093184 more,nonn
%O A093184 1,2
%A A093184 _Enoch Haga_, Mar 30 2004
%E A093184 a(9)-a(13) from _Bert Dobbelaere_, Dec 19 2018