Solutions of linear ODE with INTEGER coefficeints

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A meromorphic linear ODE can be solved by Frobenius method at a regular singular point. I'm interested in the solutions with integer coefficients, i.e. $$ f(x)=x^\alpha\sum_{n=0}^{\infty}a_nx^n,\ \ \alpha\in\mathbb{C},\ a_n\in\mathbb{Z}. $$ I would like know what kind of linear ODE has such solutions and what kind of linear ODE does not. Does anyone know criteria?