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A027495 Square of lower triangular normalized 2nd kind Stirling matrix. 6
1, 3, 1, 27, 21, 2, 173, 227, 48, 2, 2213, 4283, 1479, 134, 3, 1239065, 3303383, 1635807, 238718, 11475, 156, 1178661599, 4156965497, 2749126434, 569141150, 43679400, 1263600, 11310, 537440137205, 2439821215787, 2061668165820 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..31.

FORMULA

Numerators of lower triangle of (a[ i, j ])^2 where a[ i, j ] = S(i, j)/BellNumber(i) if j<=i, 0 if j>i

MATHEMATICA

rows = 8; m = Table[If[k <= n, StirlingS2[n, k]/BellB[n], 0], {n, 1, rows}, {k, 1, rows}]; m2 = m.m; Table[fracs = m2[[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

Cf. A008277.

Sequence in context: A269875 A271203 A271151 * A269813 A271128 A271163

Adjacent sequences:  A027492 A027493 A027494 * A027496 A027497 A027498

KEYWORD

nonn,tabl

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified March 30 06:17 EDT 2020. Contains 333119 sequences. (Running on oeis4.)