%I A001909 M3576 N1450
%S A001909 0,1,4,21,134,1001,8544,81901,870274,10146321,128718044,1764651461,
%T A001909 25992300894,409295679481,6860638482424,121951698034461,
%U A001909 2291179503374234,45361686034627361,943892592746534964
%N A001909 a(n) = n*a(n-1) + (n-4)*a(n-2).
%C A001909 With offset 1, permanent of (0,1)-matrix of size n X (n+d) with d=4 and 
               n zeros not on a line. This is a special case of Theorem 2.3 of Seok-Zun 
               Song et al. Extremes of permanents of (0,1)-matrices, p. 201-202. 
               - Jaap Spies (j.spies(AT)hccnet.nl), Dec 12 2003
%D A001909 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A001909 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A001909 Brualdi, Richard A. and Ryser, Herbert J., Combinatorial Matrix Theory, 
               Cambridge NY (1991), Chapter 7.
%D A001909 J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 
               188.
%D A001909 Seok-Zun Song et al., Extremes of permanents of (0,1)-matrices, Lin. 
               Algebra and its Applic. 373 (2003), p. 197-210.
%F A001909 E.g.f.: exp(-x)/(1-x)^5 = sum_{n>=0} a(n+3)/n! x^n. - Michael Somos, 
               Feb 19 2003
%o A001909 (PARI) a(n)=if(n<2,0,-contfracpnqn(matrix(2,n,i,j,j-4*(i==1)))[1,1])
%Y A001909 Cf. A000255, A000153, A000261, A001910, A090010, A055790, A090012-A090016.
%Y A001909 Sequence in context: A090366 A131965 A104982 this_sequence A052852 A121124 
               A087761
%Y A001909 Adjacent sequences: A001906 A001907 A001908 this_sequence A001910 A001911 
               A001912
%K A001909 nonn
%O A001909 2,3
%A A001909 N. J. A. Sloane (njas(AT)research.att.com).