DSolve::nestdv
NDSolve::nestdv
NDSolveValue::nestdv
ParametricNDSolve::nestdv
ParametricNDSolveValue::nestdv
RSolve::nestdv
Here, f[f[x]] includes f[x] as an argument of the dependent variable f:
DSolve[f'[x] == f[f[x]], f[x], x]This shows a valid input to NDSolve:
DSolve[f'[x] == f[x], f[x], x]