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 A153817 #10 May 28 2021 03:31:32
%S A153817 0,1,2,4,6,10,13,18,22,28,33,42,48,57,65,74,83,95,105,118,130,142,155,
%T A153817 171,185,200,216,232,248,270,286,307,325,345,365,390,409,433,454,480,
%U A153817 502,532,555,583,610,636,665,695,723,753,784,814,847,880,913,947,981
%N A153817 a(n)=Sum_{k=1..n} floor((n*k)/(n+k)).
%F A153817 a(n) ~ (1 - log(2)) * n^2. - _Vaclav Kotesovec_, May 28 2021
%p A153817 A153817 := proc(n) add(floor(n*k/(n+k)), k=1..n) ; end: seq(A153817(n),n=1..100) ; # _R. J. Mathar_, Feb 21 2009
%t A153817 Table[Sum[Floor[n*k/(n + k)], {k, 1, n}], {n, 1, 100}] (* _Vaclav Kotesovec_, May 28 2021 *)
%Y A153817 Cf. A000005, A006218, A118014, A153818.
%K A153817 easy,nonn
%O A153817 1,3
%A A153817 _Ctibor O. Zizka_, Jan 02 2009
%E A153817 More terms from _R. J. Mathar_, Feb 21 2009