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A238822 Number of equilateral triangles bounded by the sides and diagonals of a regular 3n-gon. 1
1, 14, 69, 188, 465, 882, 1645, 2648, 4257, 6170, 9273, 12564, 17485, 22778, 30585, 38288, 50031, 61074, 77311, 91580, 114009, 134750, 164634, 192456 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..24.

Antreas Hatzipolakis and Giovanni Resta, Number of Equilateral Triangles in Regular 3n-gon, Postings to the Sequence Fans Mailing List, Apr 08 2013

Giovanni Resta, Illustration for a(3) = 69

CROSSREFS

Cf. A006561.

Sequence in context: A075480 A236164 A254004 * A244943 A249708 A008354

Adjacent sequences:  A238819 A238820 A238821 * A238823 A238824 A238825

KEYWORD

nonn,nice,more

AUTHOR

N. J. A. Sloane, Mar 07 2014

EXTENSIONS

a(6)-a(24) from Luca Petrone, Mar 28 2017

STATUS

approved

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Last modified October 21 11:15 EDT 2019. Contains 328294 sequences. (Running on oeis4.)