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 A090541 #15 Aug 18 2019 02:50:46
%S A090541 1,4,11,20,34,51,72,97,127,161,199,242,289,341,398,459,526,597,674,
%T A090541 755,842,933,1030,1132,1240,1352,1470,1594,1723,1857,1997,2142,2293,
%U A090541 2450,2612,2780,2953,3132,3317,3508,3704,3907,4115,4328,4548,4774,5006,5243
%N A090541 a(n) = floor((Sum_{r=1..n} r)*(Sum_{r=1..n} 1/r)).
%C A090541 For large n, a(n) = floor(n*(n+1)/2)*(log(n) + 0.5772...,(Euler's constant)).
%p A090541 a:=n->floor(sum(k,k=1..n)*sum(1/k,k=1..n)):seq(a(n),n=1..56); # _Emeric Deutsch_, Apr 18 2005
%o A090541 (PARI) a(n) = floor((n*(n+1)/2)*sum(k=1, n, 1/k)); \\ _Michel Marcus_, Aug 18 2019
%Y A090541 Cf. A052488.
%K A090541 nonn
%O A090541 1,2
%A A090541 _Amarnath Murthy_, Dec 09 2003
%E A090541 More terms from _Emeric Deutsch_, Apr 18 2005