A027497 4th power of the lower triangular normalized 2nd kind Stirling matrix.

1, 15, 1, 4383, 609, 8, 332945, 70127, 1920, 8, 3818466833, 1071459023, 45021783, 392486, 675, 117707753216845145, 41103397063050887, 2332341110766495, 31497752932598, 113377876875, 94910400, 28982153439665068102728041

Offset

1,2

Links

Table of n, a(n) for n=1..22.

Formula

Numerators of lower triangle of (a[ i, j ])^4 where a[ i, j ] = S(i, j)/BellNumber(i) if j<=i, 0 if j>i

Mathematica

rows = 7; m = Table[If[k <= n, StirlingS2[n, k]/BellB[n], 0], {n, 1, rows}, {k, 1, rows}]; m4 = m.m.m.m; Table[fracs = m4[[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: A027518 A027539 A027479 * A040221 A040220 A146989

Adjacent sequences: A027494 A027495 A027496 * A027498 A027499 A027500

Keyword

nonn,tabl

Author

Olivier Gérard

Status

approved