193024domain: NAppears in sequencesNumber of 2 X 2 matrices M with all terms in {1,...,n} and permanent(M) >= n.at n=21A212240a(1)=2, a(2)=3; a(n) is the smallest k > a(n-1) such that k + a(n-1) is a multiple of a(n-2).at n=33A328724a(n) = Sum_{k=0..floor(n/3)} 2^k * binomial(2*k+1,2*n-6*k).at n=23A387766