/usr/lib/R/site-library/numDeriv/INDEX is in r-cran-numderiv 2016.8-1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 | 00.numDeriv.Intro       Accurate Numerical Derivatives
genD                    Generate Bates and Watts D Matrix
grad                    Numerical Gradient of a Function
hessian                 Calculate Hessian Matrix
jacobian                Gradient of a Vector Valued Function
numDeriv-package        Accurate Numerical Derivatives
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