  We have calculated partial contributions of different endohedral and atomic
subshells to the total dipole sum rule in the frame of the random phase
approximation with exchange (RPAE) and found that they are essentially
different from the numbers of electrons in respective subshells. This
difference manifests the strength of the intershell interaction. We present
concrete results of calculations for endohedrals, composed of fullerene C60 and
all noble gases He, Ne, Ar, Kr and Xe thus forming respectively He@C60, Ne@C60,
Ar@C60, Kr@C60, and Xe@C60. For comparison we obtained similar results for
isolated noble gas atoms. The deviation from number of electrons in outer
subshells proved to be much bigger in endohedrals than in isolated atoms thus
demonstrating considerably stronger intershell correlations there.
