已知数列{a_n}，如果$a_{1,}{a}_2-a_{1,}{a}_3-a_{2,}\cdots ,a_n-a_{n-1,\cdots }$是首项为1公比为2的等比数列，那么a_n=（   ）

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There were many famous explorers during 1400 -1600. What were the names of the most famous explorers? What were the major achievements of the famous explorers? This website provides what you want to know.

Famous Canadian Explorers

     The discovery of the New World opened up new colonies (殖民地) in Canada, One of the most famous Canadian explorers was Louis Joliet who explored the Great Lakes area and discovered the Mississippi River.

Famous Spanish Explorers

Famous Spanish explorers explored the Caribbean and South America. Just a few famous Spanish explorers conquered (征服) millions of local people who made up the nations of the Incas  and the Aztecs. Famous Spanish explorers included Hernando Cortes, Francisco Pizarro, Hernando De Soto, Vasco Nunez de Balboa and Juan Ponce de Leon.

Famous English Explorers

   The most famous English explorers started their voyages of discoveries during the Elizabethan reign of Queen Elizabeth I. The most famous English explorers included Sir Walter Raleigh, Sir Francis Drake, Sir Martin Frobisher and Sir John Hawkins.

 Famous Portuguese (葡萄牙的) Explorers      

    The famous Portuguese explorers led the way when it came to exploration. The most famous Portuguese explorers included Ferdinand Magellan, Vasco da Gama, Bartholomeu Dias and Miguel Corte-Real?