120894domain: NAppears in sequencesa(n) = 2^(n-1) + 2^[ n/2 ] + 2^[ (n-1)/2 ] - F(n+3).at n=18A005674Number of runs in all Fibonacci binary words of length n. A Fibonacci binary word is a binary word having no 00 subword. A run is a maximal sequence of consecutive identical letters.at n=19A129715