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A007402 No-3-in-line problem for equilateral triangle array of side n.
(Formerly M0123)
1
1, 1, 2, 1, 2, 15, 1, 5, 7, 971, 20, 276 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

Mohammad K. Azarian, A Trigonometric Characterization of  Equilateral Triangle, Problem 336, Mathematics and Computer Education, Vol. 31, No. 1, Winter 1997, p. 96.  Solution published in Vol. 32, No. 1, Winter 1998, pp. 84-85.

Mohammad K. Azarian, Equating Distances and Altitude in an Equilateral Triangle, Problem 316, Mathematics and Computer Education, Vol. 28, No. 3, Fall 1994, p. 337.  Solution published in Vol. 29, No. 3, Fall 1995, pp. 324-325.

R. H. Buchholz, personal communication.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Table of n, a(n) for n=1..12.

R. G. Wilson, V, Letters to N. J. A. Sloane

R. G. Wilson, V, Letter to N. J. A. Sloane, Oct. 1993

CROSSREFS

Sequence in context: A048296 A016542 A242085 * A251731 A058260 A202410

Adjacent sequences:  A007399 A007400 A007401 * A007403 A007404 A007405

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane, Mira Bernstein

STATUS

approved

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Last modified November 14 14:43 EST 2019. Contains 329126 sequences. (Running on oeis4.)