

A038590


Sizes of clusters in hexagonal lattice A_2 centered at lattice point.


5



1, 7, 13, 19, 31, 37, 43, 55, 61, 73, 85, 91, 97, 109, 121, 127, 139, 151, 163, 169, 187, 199, 211, 223, 235, 241, 253, 265, 271, 283, 295, 301, 313, 337, 349, 361, 367, 379, 385, 397, 409, 421, 433, 439, 451, 463, 475, 499, 511, 517, 535, 547
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OFFSET

0,2


COMMENTS

The hexagonal lattice is the familiar 2dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice.


REFERENCES

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", SpringerVerlag, p. 111.
B. K. Teo and N. J. A. Sloane, Atomic Arrangements and Electronic Requirements for ClosePacked Circular and Spherical Clusters, Inorganic Chemistry, 25 (1986), pp. 23152322. See Table IV.


LINKS

Table of n, a(n) for n=0..51.
G. Nebe and N. J. A. Sloane, Home page for hexagonal (or triangular) lattice A2


FORMULA

Unique(A038589). Or, partial sums of A035019.


CROSSREFS

Cf. A004016, A035019, A038589.
Sequence in context: A088513 A004611 A133290 * A218146 A129389 A107925
Adjacent sequences: A038587 A038588 A038589 * A038591 A038592 A038593


KEYWORD

nonn,easy,nice


AUTHOR

N. J. A. Sloane


STATUS

approved



