120537domain: NAppears in sequencesa(n) = Sum_{k=0..floor(n/4)} C(n-k,3*k)*3^(n-4*k).at n=10A099786Number of length 2+2 0..n arrays with the sum of the maximum minus the minimum of adjacent triples multiplied by some arrangement of +-1 equal to zero.at n=25A252178