A011949 Number of Barlow packings with group P6(bar)m2 that repeat after 2n layers.

1, 2, 6, 12, 28, 56, 119, 240, 496, 990, 2016, 4032, 8121, 16256, 32640, 65268, 130816, 261630, 523747, 1047552, 2096128, 4192200, 8386554

Offset

3,2

References

T. J. McLarnan, The numbers of polytypes ..., Zeits. Krist. 155, 269-291 (1981).

Links

Table of n, a(n) for n=3..25.

J. E. Iglesias, Enumeration of closest-packings by the space group: a simple approach, Z. Krist. 221 (2006) 237-245, Table 3.

Crossrefs

Sequence in context: A222970 A112510 A284449 * A350271 A089820 A122746

Adjacent sequences: A011946 A011947 A011948 * A011950 A011951 A011952

Keyword

nonn,easy,changed

Author

N. J. A. Sloane.

Status

approved