5.
设集合\(W\)由满足下列两个条件的数列\(\{a_{n}\}\)构成:
\(① \dfrac {a_{n}+a_{n+2}}{2} < a_{n+1}\); \(②\)存在实数\(M\),使\(a_{n}\leqslant M.(n\)为正整数\()\).
在以下数列\((1)\{n^{2}+1\}\);\((2)\{ \dfrac {2n+9}{2n+11}\}\); \((3)\{2+ \dfrac {4}{n}\}\);\((4)\{1- \dfrac {1}{2^{n}}\}\)中属于集合\(W\)的数列编号为 ______ .