%I #3 Mar 30 2012 18:59:07
%S 1,2,3,4,7,12,25,56,145,422,1389,5072,20283,87996,412663,2087868,
%T 11361831,66155642,409567833,2680486870,18465061963,133504614880,
%U 1011121118741,8008145020804,66201411633209,570006877641976
%N Diagonal sums of number triangle A107030.
%F a(n)=sum{k=0..floor(n/2), (k-1)*C(k(n-2k), n-2k)-(k-2)*sum{j=0..n-k, C(k(n-2k), j)}}
%K easy,nonn
%O 0,2
%A _Paul Barry_, May 09 2005