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A038590 Sizes of clusters in hexagonal lattice A_2 centered at lattice point. 10
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The hexagonal lattice is the familiar 2-dimensional 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", Springer-Verlag, p. 111.

B. K. Teo and N. J. A. Sloane, Atomic Arrangements and Electronic Requirements for Close-Packed Circular and Spherical Clusters, Inorganic Chemistry, 25 (1986), pp. 2315-2322. See Table IV.

LINKS

Hugo Pfoertner, Table of n, a(n) for n = 0..10000

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, A038161, A038589.

Sequence in context: A004611 A129904 A133290 * A218146 A129389 A107925

Adjacent sequences:  A038587 A038588 A038589 * A038591 A038592 A038593

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified October 16 20:36 EDT 2021. Contains 348047 sequences. (Running on oeis4.)