A248045 (2*(n-1))! * (2*n-1)! / (n * (n-1)!^3).

1, 6, 120, 4200, 211680, 13970880, 1141620480, 111307996800, 12614906304000, 1629845894476800, 236475822507724800, 38072607423743692800, 6735922851893114880000, 1299070835722243584000000, 271245990498804460339200000, 60962536364606302461235200000

Offset: 1

Author

Reinhard Zumkeller, Sep 30 2014

Keywords

• nonn

Comments

Central terms in triangles of Lah numbers: a(n) = - A008297(2*n-1,n) = A105278(2*n-1,n) = A000891(n-1)*A000142(n) = A000894(n-1)*A000142(n-1).

a(n) = n * A204515(n-1). - Reinhard Zumkeller, Oct 19 2014

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..250

Crossrefs

Cf. A000142, A000891, A000894, A008297, A105278, A204515.

Cf. A187535 (Central Lah numbers).

Programs

Haskell

a248045 n = a000891 (n - 1) * a000142 n

Formula

n*a(n) = 4*(2*n-1)*(2*n-3)*a(n-1). - R. J. Mathar, Oct 07 2014