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 A322287 #11 Sep 02 2019 08:12:42
%S A322287 0,0,1,23,210,1996,20661,205366,2048662,20502004,204951472
%N A322287 The number of odd abundant numbers below 10^n.
%C A322287 Anderson proved that the density of odd deficient numbers is at least (48 - 3*Pi^2)/(32 - Pi^2) ~ 0.831...
%C A322287 Kobayashi et al. proved that the density of odd abundant numbers is between 0.002042 and 0.002071.
%H A322287 C. W. Anderson, <a href="https://www.jstor.org/stable/2318269">Density of Deficient Odd Numbers</a>, The American Mathematical Monthly, Vol. 82, No. 10 (1975), pp. 1018-1020.
%H A322287 Mitsuo Kobayashi, Paul Pollack and Carl Pomerance, <a href="https://doi.org/10.1016/j.jnt.2008.10.011">On the distribution of sociable numbers</a>, Journal of Number Theory, Vol. 129, No. 8 (2009), pp. 1990-2009. See Theorem 10 on p. 2007.
%F A322287 Lim_{n->oo} a(n)/10^n = 0.0020... is the density of odd abundant numbers.
%e A322287 945 is the only odd abundant number below 10^3, thus a(3) = 1.
%t A322287 abQ[n_] := DivisorSigma[1, n] > 2 n; c = 0; k = 1; s = {}; Do[While[k < 10^n, If[abQ[k], c++]; k += 2]; AppendTo[s, c], {n, 1, 5}]; s
%Y A322287 Cf. A000203, A005231, A302992, A302993, A302994, A307820, A307821, A307823.
%K A322287 nonn,more
%O A322287 1,4
%A A322287 _Amiram Eldar_, Aug 28 2019