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

1,2

Comments

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

Links

Table of n, a(n) for n=1..21.

Prog

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

Crossrefs

Cf. A227791.

Sequence in context: A319321 A321574 A377583 * A375303 A020084 A325956

Adjacent sequences: A225618 A225619 A225620 * A225622 A225623 A225624

Keyword

nonn

Author

Reinhard Zumkeller, Aug 05 2013

Status

approved