CartanMatrix on CartanType
The Cartan matrix of the type in Bourbaki's numbering: the entry at row i and column j is the pairing of the simple root i with the coroot j.
Called as CombinatorialStat(x, "CartanMatrix"). The head's page has its examples.
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Distribution
Over FiniteCartanTypes at each size, tallied here in your browser; sizes past 6 are not offered.