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A048781 Number of triangles in minimal triangle graphs. 1


%S 1,2,5,13,35,86,250,687,2001,5897,17847,54683,170578,537468,1714312,

%T 5516392,17910741,58588966,193035920,640132185,2135841554,7167550473,

%U 24186506740

%N Number of triangles in minimal triangle graphs.

%C a(n) is the total number of triples in all the minimal triangle graphs on n points. That is, a(n) = Sum |T| for all A000080(n) triangle graphs G(T) on n points.

%H R. Bowen, <a href="http://dx.doi.org/10.1090/S0025-5718-1967-0223276-1">The generation of minimal triangle graphs</a>, Math. Comp. 21 (1967), 248-250.

%e For n=3 points there is one minimal triangle graph containing one triple, so a(3) = 1.

%e For n=4 points there is one triangle graph containing two triples, so a(4) = 2.

%e For n=5 points there are two graphs, containing two and three triples, respectively, so a(5) = 2+3 = 5.

%e See also the illustration in A000080.

%Y Cf. A000080.

%K nonn,more,nice

%O 3,2

%A Arlin Anderson (starship1(AT)gmail.com)

%E Edited by _N. J. A. Sloane_, Jan 22 2014

%E a(17)-a(25) from _Martin Fuller_, Mar 23 2015

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Last modified June 24 13:43 EDT 2021. Contains 345417 sequences. (Running on oeis4.)