0,4

Row sums of number triangle A123876.

a(n)=sum{k=0..n, (-1)^(n-k)*C(n,k)*(cos(2*pi*k/3)+sin(2*pi*k/3)/sqrt(3))}

Sequence in context: A066006 A112559 A030784 this_sequence A057681 A103312 A159794

Adjacent sequences: A123874 A123875 A123876 this_sequence A123878 A123879 A123880

easy,sign

Paul Barry (pbarry(AT)wit.ie), Oct 16 2006