You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.
libblas3 was reported malicious
OSV:MAL-2023-8304 - Malicious code in libblas3 (PyPI)

libblas3
0.0.1

This version was deleted from PyPI around 2023-10-13. Installing fails with:
$ pip3 install libblas3==0.0.1 ERROR: Could not find a version that satisfies the requirement libblas3==0.0.1
View other deleted versions of libblas3

Install through StableBuild

You can install this package from StableBuild's PyPI snapshots from before the version was deleted:
pip3 install \ -i https://YOUR_API_KEY.pypimirror.stablebuild.com/2023-10-12/ \ libblas3==0.0.1
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Or, download files manually

And install manually via pip:
libblas3-0.0.1.tar.gz (1.7KB)