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 A364419 #10 Apr 27 2025 03:23:17
%S A364419 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 A364419 0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,0,0,1,1,0,1,0,0,
%U A364419 1,0,0,2,0,0,1,0,0,1,0,1,1,0,0,1,0,0,1,1,0,1,0,0,1,0,0,2,0,0,1
%N A364419 Number of divisors of n of the form 5*k+3 that are at most sqrt(n).
%F A364419 G.f.: Sum_{k>=0} x^(5*k+3)^2 / (1 - x^(5*k+3)).
%t A364419 Table[Count[Divisors[n], _?(# <= Sqrt[n] && MemberQ[{3}, Mod[#, 5]] &)], {n, 99}]
%t A364419 nmax = 99; CoefficientList[Series[Sum[x^(5 k + 3)^2/(1 - x^(5 k + 3)), {k, 0, nmax}], {x, 0, nmax}], x] // Rest
%Y A364419 Cf. A001878, A038548, A364388, A364389, A364420.
%K A364419 nonn
%O A364419 1,72
%A A364419 _Ilya Gutkovskiy_, Jul 23 2023