

A027451


First diagonal of A027447.


4



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

1,3


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


LINKS

Table of n, a(n) for n=1..24.


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


MATHEMATICA

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


CROSSREFS

From Johannes W. Meijer, Jul 21 2009: (Start)
Equals A002944(n)^2.
Equals A001044(n1)/A025527(n)^2.
(End)
Sequence in context: A267898 A324981 A128524 * A227744 A035127 A061267
Adjacent sequences: A027448 A027449 A027450 * A027452 A027453 A027454


KEYWORD

nonn


AUTHOR

Olivier Gérard


EXTENSIONS

More terms from Sean A. Irvine, Nov 04 2019


STATUS

approved



