429579843435domain: NAppears in sequencesa(n) = number of integer strings s(0),...,s(n) counted by array T in A026374 that have s(n)=4; also a(n) = T(2n,n-2).at n=16A026377a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026374.at n=16A026948