0,5

Diagonal sums of triangle A123110. [From Philippe Deléham, Oct 08 2009]

Table of n, a(n) for n=0..75.

G.f.: (1-x+x^3)/(1-x-x^2+x^3)

a(n)=A110654(n-1). - R. J. Mathar, Jun 18 2008

a(n)=1/4[1-(-1)^(n-1)]+1/2*(n-1)+[C(2*n,n) mod 2] [From Paolo P. Lava, Nov 19 2008]

Cf. A065033.

Sequence in context: A080513 A004526 A140106 * A008619 A110654 A109728

Adjacent sequences: A123105 A123106 A123107 * A123109 A123110 A123111

nonn

Philippe Deléham, Sep 28 2006

approved