A certain computer program generates a sequence of numbers a1, a2, … , an such that a1 = a2 = 1 and ak = ak-1 + 2ak-2 for all integers k such that 3 ≤ k ≤ n. If n > 6, then a7 = ?
A. 32
B. 43
C. 64
D. 100
E. 128
我算的是53,没有这个答案
a1=a2=1
a3=a2+
a4=a3+
a5=a4+
a6=a5+
a7=a6+
谢谢
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