Determines if the sequence whose nth term is expr has a rational generating function. Such sequences are constructed from polynomials in n and constants to a linear power of n using the operations addition, subtraction, and multiplication.

$\mathrm{type}\left(\left(n-1\right)2^{3n+1}\,'\mathrm{ratseq}'\left(n\right)\right)$

$\mathrm{true}$

$\mathrm{type}\left({\left(n{2}^n+3-n\right)}^3\,'\mathrm{ratseq}'\left(n\right)\right)$

$\mathrm{true}$

$\mathrm{type}\left(2^{n^2}\,'\mathrm{ratseq}'\left(n\right)\right)$

$\mathrm{false}$

$\mathrm{type}\left(\frac{1}{m}\,'\mathrm{ratseq}'\left(m\right)\right)$

$\mathrm{false}$