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A057782 Building block is trapezoid formed from 3 equilateral triangles; sequence gives number of pieces (polytraps) that can be formed from n such trapezoids. 0
1, 9, 94, 1552, 27285, 509805 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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.

Computed by Brendan Owen.

LINKS

Table of n, a(n) for n=1..6.

Andrew Clarke, Other Polyforms

CROSSREFS

Cf. A000228, A000105, A058883.

Sequence in context: A048359 A307961 A099297 * A115071 A000562 A193216

Adjacent sequences:  A057779 A057780 A057781 * A057783 A057784 A057785

KEYWORD

nonn,nice

AUTHOR

N. J. A. Sloane, Oct 29 2000

EXTENSIONS

Link updated by William Rex Marshall, Dec 16 2009

STATUS

approved

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Last modified September 22 09:47 EDT 2021. Contains 347606 sequences. (Running on oeis4.)