A027495 Square of lower triangular normalized 2nd kind Stirling matrix.

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

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