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A048781 Number of triangles in minimal triangle graphs. 2
1, 2, 5, 13, 35, 86, 250, 687, 2001, 5897, 17847, 54683, 170578, 537468, 1714312, 5516392, 17910741, 58588966, 193035920, 640132185, 2135841554, 7167550473, 24186506740 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

COMMENTS

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.

LINKS

Table of n, a(n) for n=3..25.

R. Bowen, The generation of minimal triangle graphs, Math. Comp. 21 (1967), 248-250.

EXAMPLE

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

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

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

See also the illustration in A000080.

CROSSREFS

Cf. A000080.

Sequence in context: A114298 A112839 A137674 * A291242 A097919 A160438

Adjacent sequences:  A048778 A048779 A048780 * A048782 A048783 A048784

KEYWORD

nonn,more,nice

AUTHOR

Arlin Anderson (starship1(AT)gmail.com)

EXTENSIONS

Edited by N. J. A. Sloane, Jan 22 2014

a(17)-a(25) from Martin Fuller, Mar 23 2015

STATUS

approved

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Last modified February 25 00:39 EST 2018. Contains 299630 sequences. (Running on oeis4.)