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 A308812 #27 May 28 2021 03:49:52
%S A308812 1,5,13,33,61,143,246,521,985,1995,3499,7923,14028,28642,55603,115369,
%T A308812 210665,455399,838338,1755983,3383652,6974159,13034492,28011611,
%U A308812 52475486,108821068,210050941,436273458,824191369,1744975533,3301974301,6867107913,13250454241
%N A308812 a(n) = Sum_{k=1..n} binomial(n,k) * floor(n/k).
%H A308812 Robert Israel, <a href="/A308812/b308812.txt">Table of n, a(n) for n = 1..3318</a>
%F A308812 a(n) = [x^n] (1/(1 - x)) * Sum_{k=1..n} binomial(n,k) * x^k/(1 - x^k).
%F A308812 a(n) = Sum_{k=1..n} Sum_{d|k} binomial(n,d).
%F A308812 a(n) ~ 3 * 2^(n-1). - _Vaclav Kotesovec_, May 28 2021
%p A308812 f:= proc(n) local k; add(binomial(n,k)*floor(n/k),k=1..n) end proc:
%p A308812 map(f, [$1..100]); # _Robert Israel_, Aug 23 2019
%t A308812 Table[Sum[Binomial[n, k] Floor[n/k] , {k, 1, n}], {n, 1, 33}]
%t A308812 Table[SeriesCoefficient[1/(1 - x) Sum[Binomial[n, k] x^k/(1 - x^k), {k, 1, n}], {x, 0, n}], {n, 1, 33}]
%t A308812 Table[Sum[Sum[Binomial[n, d], {d, Divisors[k]}], {k, 1, n}], {n, 1, 33}]
%Y A308812 Cf. A056045.
%K A308812 nonn
%O A308812 1,2
%A A308812 _Ilya Gutkovskiy_, Aug 22 2019