For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:okurz:retry/openSUSE_Factory/home:okurz:retry.repo
zypper refresh
zypper install retry
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:okurz:retry/15.6/home:okurz:retry.repo
zypper refresh
zypper install retry
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:okurz:retry/15.5/home:okurz:retry.repo
zypper refresh
zypper install retry
For 15.4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:okurz:retry/15.4/home:okurz:retry.repo
zypper refresh
zypper install retry
For 15.3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:okurz:retry/15.3/home:okurz:retry.repo
zypper refresh
zypper install retry
For 15.2 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:okurz:retry/15.2/home:okurz:retry.repo
zypper refresh
zypper install retry
For 15.1 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:okurz:retry/15.1/home:okurz:retry.repo
zypper refresh
zypper install retry