16. Write an expression for the general or oth term, a,, of the sequence 3, 6, 12, 24, .... 17. Write the first 10 terms of the Fibonacci sequence. 18. Represent the map below as a graph where each vertex represents a country and each edge represents a common border between the countries. BURKINA FASO SIERRA BUSIN LEONE TOGO GHANA IVORY COAST 19. The drawing below shows the floor plan of Carol Ann's Photography Studio. Construct a graph to represent the studio using the letters shown to label the vertices. Use the letter O to label the vertex that represents the outside of the studio. Place vertex O near the top of the graph. Quiside 20. Is it possible for a person to walk through each doorway in the house, whose floor plan is below, without using any of the doorways twice? If so, indicate in which room the person may start, which room to go to in order, and where he or she will end. 21. Find an Euler circuit in the following graph