A089506 Denominators used in A089505 to compute column sequences of triangle A089504.

1, 3, 27, 513, 540702, 8891844390, 27306854121690, 94235953573952190, 1684561906087969348440, 1106757172299795861925080, 8644064410182787098480243878401800, 289900692457541891469406183557646377576408600, 1206267931807293851480420134690207296382114287151076400

Offset

1,2

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..50

Formula

a(n) = lcm(seq(denominator(a(n, m)), m=1..n)) with the a(n, m) formula given in A089505(n, m) but without the D(n) factor in front and lcm denotes the least common multiple of a set of numbers.

Mathematica

a[n_, m_] := (-1)^(n-m)*FactorialPower[m+2, 3]^(n-1)/(Product[ FactorialPower[m+2, 3] - FactorialPower[r+2, 3], {r, 1, m-1}]*Product[ FactorialPower[r+2, 3] - FactorialPower[m+2, 3], {r, m+1, n}]); a[n_] := LCM @@ Table[Denominator[a[n, m]], {m, 1, n}]; Array[a, 11] (* Jean-François Alcover, Sep 02 2016 *)

Crossrefs

Sequence in context: A111844 A277352 A118714 * A370578 A062496 A222844

Adjacent sequences: A089503 A089504 A089505 * A089507 A089508 A089509

Keyword

nonn,easy

Author

Wolfdieter Lang, Dec 01 2003

Extensions

a(12)-a(13) from Vincenzo Librandi, Mar 15 2018

Status

approved