This site is supported by donations to The OEIS Foundation.

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 (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 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: A004611 A129904 A133290 * A218146 A129389 A107925 Adjacent sequences:  A038587 A038588 A038589 * A038591 A038592 A038593 KEYWORD nonn,easy,nice AUTHOR STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.