a(n) is the number of relations from an n-element set into a set of at most n elements.

A344260

a(n) is the number of relations from an n-element set into a set of at most n elements.

Terms

    a(0) =1a(1) =3a(2) =21a(3) =585a(4) =69905a(5) =34636833a(6) =69810262081

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