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A217720 Number of one-sided polydrafters with n cells. 2
2, 8, 28, 116, 474, 2001, 8508 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A polydrafter is a plane figure formed by joining equal triangles with angles of 30, 60, and 90 degrees with certain restrictions on how they are joined.  See A056842 for details.  One-sided means that distinct mirror images are counted separately.

For odd n, an n-drafter cannot have mirror symmetry, so odd entries in this sequence are double those in A056842.

REFERENCES

Ed Pegg, Jr., Polyform puzzles, in Tribute to a Mathemagician, Peters, 2005, pp. 119-125.

LINKS

Table of n, a(n) for n=1..7.

K. Ishino, Polydrafters

Bernd Karl Rennhak, Drafter

EXAMPLE

There are 6 two-sided didrafters, two have distinct mirror images, so there are 8 one-sided didrafters. Thus a(2) = 8.

CROSSREFS

Cf. A056842 (number of two-sided polydrafters).

Sequence in context: A151299 A150717 A150718 * A151300 A150719 A150720

Adjacent sequences:  A217717 A217718 A217719 * A217721 A217722 A217723

KEYWORD

nonn,more

AUTHOR

George Sicherman, Mar 21 2013

STATUS

approved

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Last modified January 25 06:09 EST 2021. Contains 340416 sequences. (Running on oeis4.)