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 A321048 #11 May 17 2023 12:25:34 %S A321048 0,2,3,6,12,24,44,84,159,300,564,1064,2004,3774,7107,13386,25208, %T A321048 47472,89400,168360,317055,597080,1124424,2117520,3987720,7509690, %U A321048 14142275,26632782,50154948,94451976,177872292,334969724,630816159,1187955204,2237161404 %N A321048 Number of permutations of [n] with no fixed points where the maximal displacement of an element equals two. %H A321048 Alois P. Heinz, <a href="/A321048/b321048.txt">Table of n, a(n) for n = 2..2000</a> %H A321048 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,0,0,-2,1). %F A321048 G.f.: (x-2)*x^3/((x-1)*(x+1)*(x^4-2*x^3+x^2-2*x+1)). %F A321048 a(n) = A033305(n) - A059841(n). %F A321048 a(n) = 2*a(n-1) - 2*a(n-5) + a(n-6). - _Wesley Ivan Hurt_, May 17 2023 %Y A321048 Column k=2 of A259784. %Y A321048 Cf. A059841, A033305. %K A321048 nonn,easy %O A321048 2,2 %A A321048 _Alois P. Heinz_, Oct 26 2018