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

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

Table of n, a(n) for n=1..37.

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

Adjacent sequences: A011946 A011947 A011948 * A011950 A011951 A011952

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

More terms from M. F. Hasler, May 28 2025

Status

approved