共50条信息
已知数列\(\{ a_{n}\}\)的前\(n\)项和\(S_{n}{=}n^{2}\),则\(a_{3}{-}a_{2}\)的值为\((\) \()\)
在数列\(\{a_{n}\}\)中,\(a_{1}=1\),\({{a}_{n}}=1+\dfrac{{{\left( -1 \right)}^{n}}}{{{a}_{n-1}}}(n\geqslant 2)\),则\(a_{5}\)等于
已知数列\(\{a_{n}\}\)满足\(S_{n}+a_{n}=2n+1\),\((n∈N*)\)
\((\)Ⅰ\()\)求出\(a_{1}\),\(a_{2}\),\(a_{3}\)的值;
\((\)Ⅱ\()\)由\((\)Ⅰ\()\)猜测\(a_{n}\)的表达式,并用数学归纳法证明所得结论.
已知数列\(\left\{{a}_{n}\right\} \)的前\(n \)项和为\({S}_{n} \),\({a}_{1}=2 \),\({a}_{n+1}-{S}_{n}=2\left(n∈{N}^{*}\right) \),则\({a}_{n}= \) .
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