A formula for T(n.k) http://oeis.org/A076264 might be guessable, after the formula for column 2 given in http://oeis.org/A076264 a(n)=sum{k=0..floor(n/3), binomial(n-2k, k)(-1)^k*3^(n-3k)} with the right generalization (I didn't stumble into it though). rhhardin at mindspring.com rhhardin at att.net (either)