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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, 117649, 117649, 16807, 49, 9, 81, 117369, 59049, 33480783, 930196594089, 4238886345135097131, 169560200598623521407 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS 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}] (* 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 (PARI) for(n=1, 25, a=mathilbert(n); print1(1 / (matdet(a) * denominator(matpermanent(a)))", ")) \\ Vaclav Kotesovec, Aug 13 2021 CROSSREFS Cf. A005249. Sequence in context: A163197 A347591 A267544 * A076008 A232944 A185891 Adjacent sequences:  A061911 A061912 A061913 * A061915 A061916 A061917 KEYWORD nonn 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 a(24)-a(34) from Vaclav Kotesovec, Aug 14 2021 a(35) from Vaclav Kotesovec, Aug 16 2021 STATUS approved

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Last modified September 25 12:38 EDT 2021. Contains 347654 sequences. (Running on oeis4.)