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 A293043 #7 Feb 18 2019 10:22:55
%S A293043 0,0,0,0,2,7,49,336,2708,24398,244298,2689664,32297990,420096141,
%T A293043 5883813379,88287031264,1412982765800,24026200566396,432554403678612,
%U A293043 8219863859175936,164419973194802826,3453229295483253843,75978854506098366005,1747670263607990439472
%N A293043 Number of odd permutations p of {1,...,n} such that p(i) is not i or i+1.
%H A293043 Dmitry Efimov, <a href="https://arxiv.org/abs/1702.05655">Determinants of generalized binary band matrices</a>, arXiv:1702.05655 [math.RA], 2017.
%F A293043 a(n) = (A000271(n) + (-1)^n * floor((n-1)/2))/2.
%t A293043 a[n_] := (Sum[(-1)^(n-k) k! Binomial[n+k, 2 k], {k, 0, n}] + (-1)^n* Floor[(n - 1)/2])/2; Table[a[n], {n, 0, 23}] (* _Jean-François Alcover_, Feb 18 2019 *)
%Y A293043 Cf. A000271, A293042.
%K A293043 nonn
%O A293043 0,5
%A A293043 _Eric M. Schmidt_, Sep 28 2017