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Number of unlabeled 3-uniform hypergraphs spanning n vertices.
13

%I #13 Sep 04 2023 02:49:51

%S 1,0,0,1,3,29,2102,7011184,1788775603336,53304526022885280592,

%T 366299663378889804782337225824,

%U 1171638318502622784366970315264281830913536,3517726593606524901243694560022510194223171115509135178240

%N Number of unlabeled 3-uniform hypergraphs spanning n vertices.

%C 3-uniform means that every edge consists of 3 vertices. - _Brendan McKay_, Sep 03 2023

%H Andrew Howroyd, <a href="/A322451/b322451.txt">Table of n, a(n) for n = 0..25</a>

%e Non-isomorphic representatives of the a(5) = 29 hypergraphs:

%e {{125}{345}}

%e {{123}{245}{345}}

%e {{135}{245}{345}}

%e {{145}{245}{345}}

%e {{123}{145}{245}{345}}

%e {{124}{135}{245}{345}}

%e {{125}{135}{245}{345}}

%e {{134}{235}{245}{345}}

%e {{145}{235}{245}{345}}

%e {{123}{124}{135}{245}{345}}

%e {{123}{145}{235}{245}{345}}

%e {{124}{134}{235}{245}{345}}

%e {{134}{145}{235}{245}{345}}

%e {{135}{145}{235}{245}{345}}

%e {{145}{234}{235}{245}{345}}

%e {{123}{124}{134}{235}{245}{345}}

%e {{123}{134}{145}{235}{245}{345}}

%e {{123}{145}{234}{235}{245}{345}}

%e {{124}{135}{145}{235}{245}{345}}

%e {{125}{135}{145}{235}{245}{345}}

%e {{135}{145}{234}{235}{245}{345}}

%e {{123}{124}{135}{145}{235}{245}{345}}

%e {{124}{135}{145}{234}{235}{245}{345}}

%e {{125}{135}{145}{234}{235}{245}{345}}

%e {{134}{135}{145}{234}{235}{245}{345}}

%e {{123}{124}{135}{145}{234}{235}{245}{345}}

%e {{125}{134}{135}{145}{234}{235}{245}{345}}

%e {{124}{125}{134}{135}{145}{234}{235}{245}{345}}

%e {{123}{124}{125}{134}{135}{145}{234}{235}{245}{345}}

%Y First differences of A000665.

%Y Cf. A006126, A006129, A038041, A299471, A301922, A302374, A302394, A306017, A306021.

%K nonn

%O 0,5

%A _Gus Wiseman_, Dec 09 2018

%E a(12) from _Andrew Howroyd_, Dec 15 2018

%E Name corrected by _Brendan McKay_, Sep 03 2023