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 A230293 #18 Apr 12 2024 03:54:33
%S A230293 1,0,1,3,1,1,3,3,3,6,2,1,7,5,6,6,4,6,8,7,6,8,8,8,10,6,8,15,11,10,10,8,
%T A230293 8,14,12,11,17,15,15,15,11,10,16,14,15,17,13,19,21,19,17,17,19,17,22,
%U A230293 15,15,21,21,23,21,21,21,27,23,22,24,20,22,28,22,21,31,25,23,27,25,28,30,28,26,28,30,30,30,26,28
%N A230293 a(n) = Sum_{i=1..n} d(8*i+1) - Sum_{i=1..n} d(4*i+1), where d(n) = A000005(n).
%H A230293 Amiram Eldar, <a href="/A230293/b230293.txt">Table of n, a(n) for n = 1..10000</a>
%H A230293 Jorge Luis Cimadevilla Villacorta, <a href="http://www.jstor.org/stable/10.4169/amer.math.monthly.120.09.832">Certain inequalities associated with the divisor function</a>, Amer. Math. Monthly, 120 (2013), 832-837. (Shows that a(n) >= 0.)
%F A230293 a(n) = A230476(n) - A230294(n). - _Jonathan Sondow_, Oct 20 2013
%F A230293 a(n) = (log(2)/2) * n + O(n^(1/3)*log(n)). - _Amiram Eldar_, Apr 12 2024
%p A230293 See A230290.
%t A230293 Accumulate[Table[DivisorSigma[0, 8*n + 1] - DivisorSigma[0, 4*n + 1], {n, 1, 100}]] (* _Amiram Eldar_, Apr 12 2024 *)
%o A230293 (PARI) vector(100, n, sum(i=1, n, numdiv(8*i+1)) - sum(i=1, n, numdiv(4*i+1))) \\ _Michel Marcus_, Oct 09 2014
%Y A230293 Cf. A000005, A230290, A230291, A230292, A230294, A230295, A230296, A230476.
%K A230293 nonn
%O A230293 1,4
%A A230293 _N. J. A. Sloane_, Oct 17 2013