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 A154658 #21 Jan 29 2019 10:36:36 %S A154658 1,1,2,6,24,120,720,5040,40320,362880,3628800,33022080,277280640, %T A154658 2184341040,16427628720,119892387720,861175365144,6157828055310, %U A154658 44222780245622,321113303226243,2369364111428885,17667206334000068,132553643382927196,997400200347756816 %N A154658 Number of permutations of length n within distance 9. %C A154658 a(n) equals the permanent of the n X n matrix with 1's along the central nineteen diagonals, and 0's everywhere else. - _John M. Campbell_, Jul 10 2011 %H A154658 Alois P. Heinz, <a href="/A154658/b154658.txt">Table of n, a(n) for n = 0..400</a> (terms n=1..45 from R. H. Hardin) %H A154658 Torleiv Kløve, <a href="http://www.ii.uib.no/publikasjoner/texrap/pdf/2008-376.pdf">Spheres of Permutations under the Infinity Norm - Permutations with limited displacement</a>, Reports in Informatics, Department of Informatics, University of Bergen, Norway, no. 376, November 2008. %Y A154658 Cf. A000045, A002524, A002526, A072856, A154654-A154657. %Y A154658 Column k=9 of A306209. %K A154658 nonn %O A154658 0,3 %A A154658 _Torleiv Kløve_, Jan 13 2009 %E A154658 a(0)=1 prepended by _Alois P. Heinz_, Jan 28 2019