Search: id:A090012
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%I A090012
%S A090012 3,9,39,213,1395,10617,91911,890901,9552387,112203465,1432413063,
%T A090012 19743404469,292164206259,4619383947513,77708277841575,1385712098571957,
%U A090012 26108441941918851,518231790473609481,10808479322484810087
%N A090012 Permanent of (0,1)-matrix of size n X (n+d) with d=2 and n-1 zeros not 
               on a line.
%D A090012 Brualdi, Richard A. and Ryser, Herbert J., Combinatorial Matrix Theory, 
               Cambridge NY (1991), Chapter 7.
%D A090012 Seok-Zun Song et al., Extremes of permanents of (0,1)-matrices, Lin. 
               Algebra and its Applic. 373 (2003), p. 197-210.
%F A090012 a(n) = (n+1)*a(n-1) + (n-2)*a(n-2), a(1)=3, a(2)=9
%p A090012 A090012 := proc(n,d) local r; if (n=1) then r := d+1 elif (n=2) then 
               r := (d+1)^2 else r := (n+d-1)*A090012(n-1,d)+(n-2)*A090012(n-2,d) 
               fi; RETURN(r); end: seq(A090012(n,2),n=1..20);
%Y A090012 a(n) = A000153(n-1) + A000153(n), a(1)=3
%Y A090012 Cf. A000255, A000153, A000261, A001909, A001910, A090010, A055790, A090013-A090016.
%Y A090012 Sequence in context: A130905 A030799 A058105 this_sequence A079096 A143293 
               A101395
%Y A090012 Adjacent sequences: A090009 A090010 A090011 this_sequence A090013 A090014 
               A090015
%K A090012 nonn,easy
%O A090012 1,1
%A A090012 Jaap Spies (j.spies(AT)hccnet.nl), Dec 13 2003
%E A090012 Corrected by Jaap Spies (j.spies(AT)hccnet.nl), Jan 26 2004

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