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Search: id:A011946
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| A011946 |
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Number of Barlow packings with group P63/mmc(S) that repeat after 4n layers. |
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+0
1
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| 1, 2, 3, 8, 15, 30, 63, 128, 252, 510, 1023, 2040
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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T. J. McLarnan, The numbers of polytypes ..., Zeits. Krist. 155, 269-291 (1981).
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MAPLE
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BB:=n->n*floor(2^n/n/2): seq(BB(n), n=1..57); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 02 2007
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CROSSREFS
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Sequence in context: A099428 A099920 A128022 this_sequence A166920 A080206 A132862
Adjacent sequences: A011943 A011944 A011945 this_sequence A011947 A011948 A011949
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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