\[\boxed{\text{528.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[\textbf{а)}\ a_{100},a_{201},\ a_{n + 1},\ a_{n},\ a_{n + 2},\ a_{2n + 1};\]
\[\textbf{б)}\ \ a_{70},a_{99},\ a_{n - 3},\ a_{n + 2},\ a_{3n - 1}.\]