144141domain: NAppears in sequencesList of words over {1,4} with equal numbers of 1's and 4's.at n=16A214521Number of n X 4 0..1 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing.at n=24A223834a(n) = Sum_{k=0..floor(n/3)} 2^k * binomial(2*n-4*k+1,2*k).at n=14A387625