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A061914 Let H_n = n-th Hilbert matrix; sequence gives 1 / ( det(H_n) * denominator(permanent(H_n)) ). 1
1, 1, 1, 27, 567, 1, 1, 1, 7, 9, 5103, 1275989841, 992436543, 48629390607, 169706648853, 40257567, 63, 1, 7, 31, 1, 3969, 25865973 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..23.

Eric Weisstein's World of Mathematics, Permanent.

FORMULA

a(n) = 1/(denominator(permanent(hilbert(n)))*det(hilbert(n))), where hilbert(n) denotes the n-th Hilbert matrix.

MAPLE

with(linalg): seq(1/(denom(permanent(hilbert(n)))*det(hilbert(n))), n=1..16);

MATHEMATICA

Permanent[m_List] := With[{v = Array[x, Length[m]]}, Coefficient[Times @@ (m.v), Times @@ v]]; f[n_] := Block[{i = Table[1/(i + j - 1), {i, n}, {j, n}]}, 1/(Det[i]Denominator[Permanent[i]])]; Table[ f[n], {n, 1, 18}] (from Robert G. Wilson v Feb 06 2004)

PROG

(PARI) permRWN(a)=n=matsize(a)[1]; if(n==1, return(a[1, 1])); n1=n-1; sg=1; m=1; nc=0; in=vector(n); x=in; for(i=1, n, x[i]=a[i, n]-sum(j=1, n, a[i, j])/2); p=prod(i=1, n, x[i]); while(m, sg=-sg; j=1; if((nc%2)!=0, j++; while(in[j-1]==0, j++)); in[j]=1-in[j]; nc+=2*in[j]-1; m=nc!=in[n1]; z=2*in[j]-1; for(i=1, n, x[i]+=z*a[i, j]); p+=sg*prod(i=1, n, x[i])); return(2*(2*(n%2)-1)*p) for(n=1, 23, a=mathilbert(n); print1(1/(matdet(a)*denominator(permRWN(a)))", ")) - Herman Jamke (hermanjamke(AT)fastmail.fm), May 10 2007

CROSSREFS

Cf. A005249.

Sequence in context: A163199 A051561 A163197 * A076008 A232944 A185891

Adjacent sequences:  A061911 A061912 A061913 * A061915 A061916 A061917

KEYWORD

nonn,more

AUTHOR

Asher Auel (asher.auel(AT)reed.edu), May 20 2001

EXTENSIONS

a(18)-a(20) from Robert G. Wilson v, Feb 09 2004

a(21) from Eric W. Weisstein, Feb 19, 2004

a(22) and a(23) from Herman Jamke (hermanjamke(AT)fastmail.fm), May 10 2007

STATUS

approved

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Last modified April 17 17:33 EDT 2014. Contains 240650 sequences.