A225621 - OEIS

%I #13 Aug 05 2013 13:45:24

%S 1,4,20,108,632,4060,28968,231000,2058096,20375964,222393800,

%T 2653879624,34365597840,479776469848,7181892528272,114731622081840,

%U 1948073992109280,35031456100431900,665075537735997960,13292908401187179240,279000321119414475600

%N Central terms of the triangle in A074911.

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

%o (Haskell)

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

%Y Cf. A227791.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Aug 05 2013