问题补充:刚打错了,是求{an/bn}的的前n项和 an=a1+(n-1)d=b2=q^1=q,b3=q^2 1+d+q=5 (1) 1+4d+q^2=13 (2) (2)-(
设an=1+3+5+...+(2n+1),定义数列{bn}如下:bn即为an的各位数字,那么b1+b2+b3+...+b
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