A027451 - OEIS

%I #19 Nov 04 2019 20:39:41

%S 1,1,4,9,144,100,3600,11025,78400,63504,6350400,5336100,768398400,

%T 662547600,577152576,2029052025,519437318400,463325262400,

%U 150117385017600,135480939978384,122885206329600,111967718990400,54192375991353600,49770428644836900

%N First diagonal of A027447.

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

%C It appears that a(n) = denominator of n^2*sum(1/k^2,k=1..n). - _Gary Detlefs_, May 29 2010

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

%F a(n) = (lcm($1..n)/n)^2. - _Johannes W. Meijer_, Jul 21 2009

%t a[n_] := (LCM @@ Range[n]/n)^2; Table[a[n], {n, 1, 20}] (* _Jean-François Alcover_, Mar 05 2013, after _Johannes W. Meijer_ *)

%Y From _Johannes W. Meijer_, Jul 21 2009: (Start)

%Y Equals A002944(n)^2.

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

%Y (End)

%K nonn

%O 1,3

%A _Olivier Gérard_

%E More terms from _Sean A. Irvine_, Nov 04 2019