%I
%S 1,2,8,18,78,206,872,2226,10820,26558,129248,335886,1630174,3990978,
%T 21778450,48749804,274937594,650637382,3598954596,7610277626,
%U 49741540498,93757794966,639655810986,1233712869392,8530089042832
%N Alternating row sums of triangle A134285, called s2(3)'.
%F a(n))=sum(A134285(n,m)*(1)^(m1),m=1..n), n>=1.
%Y Cf. A134826 (row sums of triangle A134285).
%K nonn,easy
%O 1,2
%A _Wolfdieter Lang_ Nov 13 2007
