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 A226282 #18 Jul 12 2024 15:21:56
%S A226282 0,1,4,16,72,324,1728,9216,57600,360000,2592000,18662400,152409600,
%T A226282 1244678400,11379916800,104044953600,1053455155200,10666233446400,
%U A226282 118513704960000,1316818944000000,15933509222400000,192795461591040000,2523867860828160000,33039724723568640000
%N A226282 a(n) = [n/2]!*[(n+1)/2]!*C([n/2],1)*C([(n+1)/2],1).
%C A226282 Number of permutations of n elements with 2 odd displacements.
%C A226282 Column 2 of A226288.
%C A226282 Column k=2 of A145893, a diagonal of A145894. - _Alois P. Heinz_, May 29 2014
%H A226282 R. H. Hardin, <a href="/A226282/b226282.txt">Table of n, a(n) for n = 1..210</a>
%t A226282 Table[Floor[n/2]!Floor[(n+1)/2]!Binomial[Floor[n/2],1]Binomial[Floor[(n+1)/2],1],{n,30}] (* _Harvey P. Dale_, Aug 05 2023 *)
%Y A226282 Cf. A145893, A145894, A226288.
%K A226282 nonn
%O A226282 1,3
%A A226282 _R. H. Hardin_, connection of formula with combinatoric problem via _N. J. A. Sloane_ in the Sequence Fans Mailing List, Jun 02 2013