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 A226998 #9 Jul 30 2016 16:26:45
%S A226998 0,1,18,288,5000,97200,2117682,51380224,1377495072,40500000000,
%T A226998 1296871230050,44952006426624,1677462128818632,67068898339975168,
%U A226998 2860906750488281250,129703669268270284800,6228632560085359165568,315864220382241648869376,16868630748261621128320242
%N A226998 The number of descents over all functions f:{1,2,...,n}->{1,2,...,n}.
%C A226998 A descent is an element j in {1,2,...,n-1} such that f(j) > f(j+1).
%F A226998 a(n) = (n + 1/n -2)*n^n/2 = A062023(n) - n^n.
%t A226998 Table[(n + 1/n -2)*n^n/2,{n,1,20}]
%Y A226998 Cf. A225753.
%K A226998 nonn
%O A226998 1,3
%A A226998 _Geoffrey Critzer_, Jun 26 2013