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 A364387 #12 Dec 29 2024 22:31:21
%S A364387 0,0,0,0,0,0,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,
%T A364387 0,1,0,0,1,0,0,1,0,0,1,0,0,1,1,0,1,0,0,1,0,1,1,0,0,1,0,0,2,0,0,1,0,0,
%U A364387 1,1,0,1,0,0,1,0,1,1,0,0,1,0,0,2,0,0,1,0,0,1,1,0,1,0,0,1,0,1,1
%N A364387 Number of divisors of n of the form 4*k+3 that are at most sqrt(n).
%H A364387 Robert Israel, <a href="/A364387/b364387.txt">Table of n, a(n) for n = 1..10000</a>
%F A364387 G.f.: Sum_{k>=0} x^(4*k+3)^2 / (1 - x^(4*k+3)).
%p A364387 f:= proc(n) nops(select(t -> t mod 4 = 3 and t^2 <= n, numtheory:-divisors(n))) end proc:
%p A364387 map(f, [$1..100]); # _Robert Israel_, Dec 29 2024
%t A364387 Table[Count[Divisors[n], _?(# <= Sqrt[n] && MemberQ[{3}, Mod[#, 4]] &)], {n, 99}]
%t A364387 nmax = 99; CoefficientList[Series[Sum[x^(4 k + 3)^2/(1 - x^(4 k + 3)), {k, 0, nmax}], {x, 0, nmax}], x] // Rest
%Y A364387 Cf. A001842, A038548, A364358.
%K A364387 nonn
%O A364387 1,63
%A A364387 _Ilya Gutkovskiy_, Jul 21 2023