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 A316681 #18 Sep 16 2018 06:52:55 %S A316681 0,0,1,2,4,5,6,8,9,11,13,14,16,18,20,22,24,26,27,29,31,34,36,38,40,42, %T A316681 44,46,48,51,53,55,57,59,62,64,66,69,71,73,76,78,80,83,85,88,90,92,95, %U A316681 97,100,102,105,107,110,112,115,117,120,122,125,127 %N A316681 a(n) = floor(n*log(n)/2). %e A316681 a(1) = floor(1*log(1)/2) = 0; %e A316681 a(2) = floor(2*log(2)/2) = 0. %t A316681 Array[Floor[#*Log[#]/2] &, 70] (* _Robert G. Wilson v_, Jul 21 2018 *) %o A316681 (PARI) a(n) = floor(n*log(n)/2); \\ _Michel Marcus_, Jul 13 2018 %Y A316681 Cf. A050504. %K A316681 nonn,easy %O A316681 1,4 %A A316681 _Marcos Librán López_, Jul 10 2018