4.
下列命题:\(①\)已知数列\(\{a\)\({\,\!}_{n}\)\(\}\),\(a\)\({\,\!}_{n}\)\(=\)\( \dfrac{1}{n(n+2)}\)\((n∈N\)\({\,\!}^{*}\)\()\),那么\( \dfrac{1}{120}\)是这个数列的第\(10\)项,且最大项为第\(1\)项;\(②\)数列\( \sqrt{2}\),\( \sqrt{5}\),\(2\)\( \sqrt{2}\),\( \sqrt{11}\),\(…\)的一个通项公式是\(a\)\({\,\!}_{n}\)\(=\)\( \sqrt{3n-1}\);\(③\)已知数列\(\{a\)\({\,\!}_{n}\)\(\}\),\(a\)\({\,\!}_{n}\)\(=kn-5\),且\(a\)\({\,\!}_{8}\)\(=11\),则\(a\)\({\,\!}_{17}\)\(=29\);\(④\)已知\(a\)\({\,\!}_{n+1}\)\(=a\)\({\,\!}_{n}\)\(+3\),则数列\(\{a\)\({\,\!}_{n}\)\(\}\)是递增数列.其中正确命题的个数为\((\) \()\)