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ModulesOfVanishingFirstExtensionWithRegularModule on DyckPath ​

The indecomposable modules with no first extension by the regular module.

On DyckPath

FindStat's St001213. Every indecomposable module is (top v - 1, length 1 .. the series' entry at v).

Called as CombinatorialStat(x, "ModulesOfVanishingFirstExtensionWithRegularModule"). The head's page has its examples.

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FindStat St001213

The number of indecomposable modules in the corresponding Nakayama algebra that have vanishing first Ext-group with the regular module.

ObjectValue
[1,0]2
[1,0,1,0]4
[1,1,0,0]3
[1,0,1,0,1,0]6
[1,0,1,1,0,0]5
[1,1,0,0,1,0]5
[1,1,0,1,0,0]6
[1,1,1,0,0,0]4

Data from FindStat, the combinatorial statistic finder; the page at findstat.org/St001213 has the rest.