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 A364420 #5 Jul 25 2023 09:18:25
%S A364420 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,
%T A364420 0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,1,
%U A364420 0,0,0,1,0,0,0,1,0,0,0,1,1,0,0,1,0,0,0,1,0,1,0,1,0,0,0,1,0,0,1,1,0,0,0,1,0,0,0,2
%N A364420 Number of divisors of n of the form 5*k+4 that are at most sqrt(n).
%F A364420 G.f.: Sum_{k>=0} x^(5*k+4)^2 / (1 - x^(5*k+4)).
%t A364420 Table[Count[Divisors[n], _?(# <= Sqrt[n] && MemberQ[{4}, Mod[#, 5]] &)], {n, 108}]
%t A364420 nmax = 108; CoefficientList[Series[Sum[x^(5 k + 4)^2/(1 - x^(5 k + 4)), {k, 0, nmax}], {x, 0, nmax}], x] // Rest
%Y A364420 Cf. A001899, A038548, A364388, A364389, A364419.
%K A364420 nonn
%O A364420 1,108
%A A364420 _Ilya Gutkovskiy_, Jul 23 2023