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Triangle read by rows: T(n,k) is the number of graphs with n vertices and minimum vertex degree k, (0 <= k < n).
9

%I #24 Mar 10 2020 23:47:31

%S 1,1,1,2,1,1,4,4,2,1,11,12,8,2,1,34,60,43,15,3,1,156,378,360,121,25,3,

%T 1,1044,3843,4869,2166,378,41,4,1,12346,64455,113622,68774,14306,1095,

%U 65,4,1,274668,1921532,4605833,3953162,1141597,104829,3441,100,5,1

%N Triangle read by rows: T(n,k) is the number of graphs with n vertices and minimum vertex degree k, (0 <= k < n).

%C Terms may be computed without generating each graph by enumerating the number of graphs by degree sequence. A PARI program showing this technique for graphs with labeled vertices is given in A327366. Burnside's lemma can be used to extend this method to the unlabeled case. - _Andrew Howroyd_, Mar 10 2020

%H Andrew Howroyd, <a href="/A294217/b294217.txt">Table of n, a(n) for n = 1..210</a> (first 20 rows)

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/MinimumVertexDegree.html">Minimum Vertex Degree</a>

%F T(n, 0) = A000088(n-1).

%F T(n, n-2) = A004526(n) for n > 1.

%F T(n, n-1) = 1.

%F T(n, k) = A263293(n, n-1-k). - _Andrew Howroyd_, Sep 03 2019

%e Triangle begins:

%e 1;

%e 1, 1;

%e 2, 1, 1;

%e 4, 4, 2, 1;

%e 11, 12, 8, 2, 1;

%e 34, 60, 43, 15, 3, 1;

%e 156, 378, 360, 121, 25, 3, 1;

%e ...

%Y Row sums are A000088 (simple graphs on n nodes).

%Y Columns k=0..2 are A000088(n-1), A324693, A324670.

%Y Cf. A263293 (triangle of n-node maximum vertex degree counts).

%Y The labeled version is A327366.

%Y Cf. A002494, A004110, A261919, A327227, A327230, A327335, A327372.

%K nonn,tabl

%O 1,4

%A _Eric W. Weisstein_, Oct 25 2017

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Last modified September 24 05:38 EDT 2024. Contains 376185 sequences. (Running on oeis4.)