For openSUSE Leap 15.2 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:embar-/openSUSE_Leap_15.2/home:embar-.repo
zypper refresh
zypper install R-base
For openSUSE Leap 15.1 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:embar-/openSUSE_Leap_15.1/home:embar-.repo
zypper refresh
zypper install R-base
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:embar-/15.4/home:embar-.repo
zypper refresh
zypper install R-base