A027451 First diagonal of A027447.

1, 1, 4, 9, 144, 100, 3600, 11025, 78400, 63504, 6350400, 5336100, 768398400, 662547600, 577152576, 2029052025, 519437318400, 463325262400, 150117385017600, 135480939978384, 122885206329600, 111967718990400, 54192375991353600, 49770428644836900

Offset: 1

Author

Olivier Gérard

Keywords

• nonn

Comments

Equals the denominators of MN(z;n)/(n!)^2 for n =>1, see A162990. - Johannes W. Meijer, Jul 21 2009

It appears that a(n) = denominator of n^2*sum(1/k^2,k=1..n). - Gary Detlefs, May 29 2010

Crossrefs

From Johannes W. Meijer, Jul 21 2009: (Start)

Equals A002944(n)^2.

Equals A001044(n-1)/A025527(n)^2.

(End)

Programs

Mathematica

a[n_] := (LCM @@ Range[n]/n)^2; Table[a[n], {n, 1, 20}] (* Jean-François Alcover, Mar 05 2013, after Johannes W. Meijer *)

Formula

Numerators of sequence a[ n, n ] in (a[ i, j ])^3 where a[ i, j ] = 1/i if j<=i, 0 if j>i.

a(n) = (lcm($1..n)/n)^2. - Johannes W. Meijer, Jul 21 2009

Extensions

More terms from Sean A. Irvine, Nov 04 2019