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 A345445 #16 May 22 2022 16:39:18
%S A345445 0,1,15,196,2765,44136,803383,16595776,385606089,9980041600,
%T A345445 285072169811,8912986937856,302831517446653,11111352988374016,
%U A345445 437883428985915375,18446566229995503616,827237060699483900177,39346347252746333159424,1978418439209309500803979,104857574454528914145280000
%N A345445 a(n) = n^n - (n+1)!/2.
%C A345445 This sequence appears as a class of nonsortable words of length n for several unadapted sorting algorithms. For instance this one:
%C A345445 - scan all values not at their index position
%C A345445 - rotate left 1 step all of them as a cycle
%C A345445 - repeat.
%C A345445 This is linked to the fact that one can encode the alternating permutations of length n+1 as words of length n.
%t A345445 Table[n^n - (n + 1)!/2, {n, 1, 20}]
%Y A345445 Cf. A185391 (Complement to n^n of a class of words).
%K A345445 nonn,easy
%O A345445 1,3
%A A345445 _Olivier Gérard_, Jun 19 2021