A225621 Central terms of the triangle in A074911.

1, 4, 20, 108, 632, 4060, 28968, 231000, 2058096, 20375964, 222393800, 2653879624, 34365597840, 479776469848, 7181892528272, 114731622081840, 1948073992109280, 35031456100431900, 665075537735997960, 13292908401187179240, 279000321119414475600

Offset: 1

Author

Reinhard Zumkeller, Aug 05 2013

Keywords

• nonn

Comments

a(n) = A074911(2*n-1,n).

Crossrefs

Cf. A227791.

Programs

Haskell

a225621 n = a074911 (2 * n - 1) n