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A011949
Number of Barlow packings with group P6(bar)m2 that repeat after 2n layers.
1
0, 0, 1, 2, 6, 12, 28, 56, 119, 240, 496, 990, 2016, 4032, 8121, 16256, 32640, 65268, 130816, 261630, 523747, 1047552, 2096128, 4192200, 8386554, 16773120, 33550216, 67100670, 134209536, 268418820, 536854528, 1073709056, 2147450383, 4294901760, 8589869022, 17179737120, 34359607296
OFFSET
1,4
LINKS
J. E. Iglesias, Enumeration of closest-packings by the space group: a simple approach, Z. Krist. 221 (2006) 237-245, Table 3.
T. J. McLarnan, The numbers of polytypes in close packings and related structures, Zeitschr. Krist. 155, 269-291 (1981).
CROSSREFS
Sequence in context: A112510 A384497 A284449 * A350271 A089820 A122746
KEYWORD
nonn,easy
EXTENSIONS
More terms from M. F. Hasler, May 28 2025
STATUS
approved