%I A002526 M1671 N0657
%S A002526 1,1,2,6,24,78,230,675,2069,6404,19708,60216,183988,563172,1725349,
%T A002526 5284109,16177694,49526506,151635752,464286962,1421566698,4352505527,
%U A002526 13326304313,40802053896,124926806216,382497958000,1171122069784
%N A002526 Number of permutations of length n within distance 3.
%D A002526 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A002526 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A002526 R. Lagrange, Quelques re'sultats dans la me'trique des permutations, 
               Annales Scientifiques de l'\'{E}cole Normale Sup\'{e}rieure, Paris, 
               79 (1962), 199-241.
%D A002526 D. H. Lehmer, Permutations with strongly restricted displacements. Combinatorial 
               theory and its applications, II (Proc. Colloq., Balatonfured, 1969), 
               pp. 755-770. North-Holland, Amsterdam, 1970.
%H A002526 R. Lagrange, <a href="http://archive.numdam.org/article/ASENS_1962_3_79_3_199_0.pdf">
               Quelques re'sultats dans la me'trique des permutations</a>, Annales 
               Scientifiques de l'\'{E}cole Normale Sup\'{e}rieure, Paris, 79 (1962), 
               199-241.
%H A002526 Torleiv Klove, <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.
%F A002526 G.f.: (1-x-2*x^2-2*x^4+x^7+x^8)/(1-2*x-2*x^2-10*x^4-8*x^5+2*x^6+16*x^7+10*x^8+2*x^9-4*x^10-2*x^11-2*x^13-x^14\
               )
%Y A002526 Sequence in context: A147938 A147929 A147921 this_sequence A117665 A068777 
               A095110
%Y A002526 Adjacent sequences: A002523 A002524 A002525 this_sequence A002527 A002528 
               A002529
%K A002526 nonn,easy,nice
%O A002526 0,3
%A A002526 N. J. A. Sloane (njas(AT)research.att.com).