The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A366486 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A366486

Place n equally spaced points on each side of an equilateral triangle, and join each of these points by a chord to the 2*n new points on the other two sides: sequence gives number of regions in the resulting planar graph.
(history; published version)

#21 by Michael De Vlieger at Sun Nov 12 00:07:16 EST 2023

STATUS

proposed

approved

#20 by Scott R. Shannon at Sat Nov 11 22:21:36 EST 2023

STATUS

editing

proposed

#19 by Scott R. Shannon at Sat Nov 11 22:21:29 EST 2023

FORMULA

a(n) = A366483(n) + A366485(n) - A366483(n) + 1 (Euler).

STATUS

approved

editing

Discussion

Sat Nov 11

22:21

Scott R. Shannon: Fixing formula

#18 by N. J. A. Sloane at Sat Nov 11 00:24:11 EST 2023

STATUS

editing

approved

#17 by N. J. A. Sloane at Sat Nov 11 00:24:08 EST 2023

LINKS

N. J. A. Sloane, <a href="/A366483/a366483_2.pdf">My notes on these triangles</a>. [To be discarded once we have better pictures]

N. J. A. Sloane, <a href="/A366483/a366483.pdf">Sketch of the graph for n = 2</a>. [To be discarded once we have better pictures]

N. J. A. Sloane, <a href="/A366483/a366483_1.pdf">The graph for n = 3</a>.

EXTENSIONS

Under construction, do not touch.

#16 by Scott R. Shannon at Fri Nov 10 18:57:54 EST 2023

CROSSREFS

Cf. A366483 (vertices), A366484 (interior vertices), A2366485 A366485 (edges).

#15 by Scott R. Shannon at Fri Nov 10 18:57:05 EST 2023

CROSSREFS

Cf. A3366483 A366483 (vertices), A366484 (interior vertices), A2366485 (edges).

#14 by Scott R. Shannon at Fri Nov 10 06:59:47 EST 2023

LINKS

N. J. A. Sloane, <a href="/A366483/a366483_2.pdf">My notes on these triangles</a> [To be discarded once we have better pictures]

N. J. A. Sloane, <a href="/A366483/a366483.pdf">Sketch of the graph for n = 2</a> [To be discarded once we have better pictures]

N. J. A. Sloane, <a href="/A366483/a366483_1.pdf">The graph for n = 3</a>

N. J. A. Sloane, <a href="/A366483/a366483_2.pdf">My notes on these triangles</a>. [To be discarded once we have better pictures]

N. J. A. Sloane, <a href="/A366483/a366483.pdf">Sketch of the graph for n = 2</a>. [To be discarded once we have better pictures]

N. J. A. Sloane, <a href="/A366483/a366483_1.pdf">The graph for n = 3</a>.

#13 by Scott R. Shannon at Fri Nov 10 06:59:10 EST 2023

LINKS

Scott R. Shannon, <a href="/A366486/a366486_5.png">Image for n = 10</a>.

#12 by Scott R. Shannon at Fri Nov 10 06:58:36 EST 2023

LINKS

Scott R. Shannon, <a href="/A366486/a366486.png">Image for n = 1</a>.

Scott R. Shannon, <a href="/A366486/a366486_1.png">Image for n = 2</a>.

Scott R. Shannon, <a href="/A366486/a366486_2.png">Image for n = 3</a>.

Scott R. Shannon, <a href="/A366486/a366486_3.png">Image for n = 4</a>.

Scott R. Shannon, <a href="/A366486/a366486_4.png">Image for n = 5</a>.