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设数列是以2为首项,1为公差的等差数列,是以1为首项,2为公比的等比数列,则等于( )
A.78 B.84 C.124 D.126
设数列是以2为首项,1为公差的等差数列,数列是以1为首项,2为公比的等比数列, 则 = .
设等差数列的首项及公差均是正整数,前项和为,且,,,则= .
设数列是以2为首项,1为公差的等差数列,是以1为首项,2为公比的等比数列,则 ( )
A.1033 B.1034 C.2057 D.2058