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A056845 Number of polydiamonds: polyominoes made from n diamonds (another version). 1
1, 2, 9, 41, 248, 1609 (list; graph; refs; listen; history; text; internal format)



The difference between this and A056844 is not clear to me. Maybe the definition of equivalence has been changed, or the rules concerning planarity or the existence of holes have changed.

Comment from Larry_Reeves(AT)intranetsolutions.com, Jun 22 2001: If you look at Vicher's picture of the 40 4-celled polydiamonds (link in A056844), near the middle of the picture is a polydiamond that looks like the traditional 2-D representation of a cube with an extra diamond stuck to the edge. Depending on how you orient the cube, there are actually 2 different ways to form this polydiamond, although there is no change in the perimeter shape. I haven't confirmed that this explains the difference in values for sizes 5 and above, but it looks like a possible explanation.


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

M. Keller, More information

M. Vicher, Polyforms


Cf. A056844.

Sequence in context: A152052 A192661 A020038 * A162273 A289684 A280955

Adjacent sequences:  A056842 A056843 A056844 * A056846 A056847 A056848




James A. Sellers, Aug 28 2000



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Last modified November 21 04:33 EST 2019. Contains 329350 sequences. (Running on oeis4.)