A086065 - OEIS

%I #2 Nov 10 2007 03:00:00

%S 0,1,6,196,5408,251132,16873158,1420208149,154380762016,

%T 20646224057048,3433326930682392,642182473998511032,

%U 152740983098362758624,40168709084329725908872,12234598116934739577149272

%N Permanent of the n X n matrix whose element (i,j) equals sigma(|i-j|) where sigma(n) is the sum of divisors of n and sigma(0) = 0.

%o (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) sgm(n)=if(n>0,sigma(n),0) for(n=1,21,a=matrix(n,n,i,j,sgm(abs(i-j)));print1(permRWNb(a)",")) - Herman Jamke (hermanjamke(AT)fastmail.fm), May 14 2007

%Y Cf. A085511.

%K nonn

%O 1,3

%A Yuval Dekel (dekelyuval(AT)hotmail.com), Aug 24 2003

%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), May 14 2007