%I A085807
%S A085807 0,1,4,64,1152,34372,1335008,69599744,4577345152,374491314176,
%T A085807 37154032517376,4402467119882240,613680867638476800,
%U A085807 99443966100565999872,18534733913629064343552,3937496200758879526977536
%N A085807 Permanent of the symmetric n X n matrix A defined by A[i,j] = |i-j| for 
               1 <= i,j <= n.
%o A085807 (PARI) permRWNb(a)=n=matsize(a)[1];if(n==1,return(a[1,1]));sg=1;in=vectorv(n);
               x=in;x=a[,n]-sum(j=1,n,a[,j])/2;p=prod(i=1,n,x[i]);for(k=1,2^(n-1)-1,
               sg=-sg;j=valuation(k,2)+1;z=1-2*in[j];in[j]+=z;x+=z*a[,j];p+=prod(i=1,
               n,x[i],sg));return(2*(2*(n%2)-1)*p) for(n=1,22,a=matrix(n,n,i,j,abs(i-j));
               print1(permRWNb(a)",")) - Herman Jamke (hermanjamke(AT)fastmail.fm), 
               May 14 2007
%Y A085807 Cf. A085750.
%Y A085807 Sequence in context: A013709 A139292 A152923 this_sequence A014729 A085532 
               A146341
%Y A085807 Adjacent sequences: A085804 A085805 A085806 this_sequence A085808 A085809 
               A085810
%K A085807 nonn
%O A085807 1,3
%A A085807 Yuval Dekel (dekelyuval(AT)hotmail.com), Jul 24 2003
%E A085807 More terms from Vladeta Jovovic (vladeta(AT)eunet.rs), Jul 26 2003