共50条信息
已知\(a_{n+1}-a_{n}-3=0\),则数列\(\{a_{n}\}\)是\((\) \()\)
\({{S}_{n}}\)为等差数列\(\left\{ {{a}_{n}} \right\}\)的前\(n\)项和,且\({a}_{1}=1,{S}_{7}=28 .\)记\({b}_{n}=[\lg {a}_{n}] \),其中\(\left[ x \right]\)表示不超过\(x\)的最大整数,如\(\left[0.9\right]=0,\left[\lg 99\right] .\)则数列\(\left\{ {{b}_{n}} \right\}\)的前\(1 000\)项和为\((\) \()\)
在数列\(\{a_{n}\}\)中,\(a_{1}=2\),\(a_{17}=66\),通项公式是关于\(n\)的一次函数.
\((1)\)求数列\(\{a_{n}\}\)的通项公式;
\((2)\)求\(a_{2016}\);
\((3)2016\)是否为数列\(\{a_{n}\}\)中的项?
设等比数列\(\left\{ {{a}_{n}} \right\}\)的公比为\(q\),前\(n\)项和为\({{T}_{n}}.(\) \()\)
已知等差数列\(\left\{ {{a}_{n}} \right\}\)中,\({{S}_{n}}\)是它的前\(n\)项和,若\({{S}_{16}} > 0\),且\({{S}_{17}} < 0\),则当\({{S}_{n}}\)取最大值时的\(n\)值为\((\) \()\)
.已知函数\(f\)\((\)\(x\)\()\)是定义在\((0,\)\(+\)\(∞\)\()\)上的单调函数,且对任意的正数\(x\),\(y\)都有\(f\)\((\)\(xy\)\()\)\(=f\)\((\)\(x\)\()\)\(+f\)\((\)\(y\)\()\).若数列\(\{\)\(a_{n}\)\(\}\)的前\(n\)项和为\(S_{n}\),且满足\(f\)\((\)\(S_{n}+\)\(2)\)\(-f\)\((\)\(a_{n}\)\()\)\(=f\)\((3)(\)\(n\)\(∈N\)\({\,\!}^{*}\)\()\),则\(a_{n}\)等于\((\) \()\)
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