${u_n} = {{2{n^5} - 7{n^2} - 3} \over {n - 3{n^5}}}$  

${u_n} = {{2{n^2} - n + 4} \over {\sqrt {2{n^4} - {n^2} + 1} }}$ 

${u_n} = {{{n^3} - {n^2}\sin 3n - 1} \over {2{n^4} - {n^2} + 7}}$ 

${u_n} = {{{{7.2}^n} + {4^n}} \over {{{2.3}^n} + {4^n}}}$

${u_n} = {{{{5.2}^n} - {3^n}} \over {{2^{n + 1}} + {3^{n + 1}}}}$     

${u_n} = \sqrt {{{{n^6} + 3{n^3} - 3} \over {2{n^6} + {n^5} + 2}}}$