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A027447 Cube of the lower triangular mean matrix. 12
1, 7, 1, 85, 19, 4, 415, 115, 37, 9, 12019, 3799, 1489, 549, 144, 13489, 4669, 2059, 919, 364, 100, 726301, 268921, 128431, 64171, 30676, 12700, 3600, 3144919, 1227199, 621139, 334699, 178669, 89125, 38025, 11025, 30300391, 12335311 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..38.

FORMULA

Numerators of lower triangle of (a[ i, j ])^3 where a[ i, j ] = 1/i if j<=i, 0 if j>i

MATHEMATICA

rows = 9; m = Table[ If[j <= i, 1/i, 0], {i, 1, rows}, {j, 1, rows}]; m3 = m.m.m; Table[ fracs = m3[[i]]; nums = fracs // Numerator; dens = fracs // Denominator; lcm = LCM @@ dens; Table[ nums[[j]]*lcm/dens[[j]], {j, 1, i}], {i, 1, rows}] // Flatten (* Jean-François Alcover, Mar 05 2013 *)

CROSSREFS

Sequence in context: A110788 A100254 A119935 * A027517 A092082 A013559

Adjacent sequences:  A027444 A027445 A027446 * A027448 A027449 A027450

KEYWORD

nonn,tabl

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified April 18 12:34 EDT 2019. Contains 322209 sequences. (Running on oeis4.)