A298036 Coordination sequence of Dual(4.6.12) tiling with respect to a 12-valent node.

1, 12, 12, 36, 24, 60, 36, 84, 48, 108, 60, 132, 72, 156, 84, 180, 96, 204, 108, 228, 120, 252, 132, 276, 144, 300, 156, 324, 168, 348, 180, 372, 192, 396, 204, 420, 216, 444, 228, 468, 240, 492, 252, 516, 264, 540, 276, 564, 288, 588, 300

Offset

0,2

Comments

Conjecture: For n>0, a(n)=6n if n even, otherwise 12n.

The conjecture can easily be shown to be true: The vertices at distance 2k consist of 3k 12-valent and 3k 4-alent vertices, and the vertices at distance 2k+1 consist of 6(k+1) 6-valent and 6(k+1) 4-valent vertices. - Charlie Neder, Apr 22 2019

Links

Hakan Icoz, Table of n, a(n) for n = 0..20000

Tom Karzes, Tiling Coordination Sequences

N. J. A. Sloane, Illustration of initial terms (shows one 60-degree sector of tiling)

N. J. A. Sloane, Overview of coordination sequences of Laves tilings [Fig. 2.7.1 of Grünbaum-Shephard 1987 with A-numbers added and in some cases the name in the RCSR database]

Index entries for linear recurrences with constant coefficients, signature (0, 2, 0, -1).

Formula

From Charlie Neder, Apr 22 2019: (Start)

a(n) = 6 * n * (1 + n mod 2), n > 0.

G.f.: (1 + 12*x + 10*x^2 + 12*x^3 + x^4)/(1 - x^2)^2. (End)

Crossrefs

Cf. A072154, A298037 (partial sums), A298038 (hexavalent node), A298040 (tetravalent node).

Cf. A109043 (a(n)/6), A026741 (a(n)/12).

List of coordination sequences for Laves tilings (or duals of uniform planar nets): [3,3,3,3,3.3] = A008486; [3.3.3.3.6] = A298014, A298015, A298016; [3.3.3.4.4] = A298022, A298024; [3.3.4.3.4] = A008574, A296368; [3.6.3.6] = A298026, A298028; [3.4.6.4] = A298029, A298031, A298033; [3.12.12] = A019557, A298035; [4.4.4.4] = A008574; [4.6.12] = A298036, A298038, A298040; [4.8.8] = A022144, A234275; [6.6.6] = A008458.

Sequence in context: A048759 A364434 A303646 * A119877 A307842 A147833

Adjacent sequences: A298033 A298034 A298035 * A298037 A298038 A298039

Keyword

nonn

Author

N. J. A. Sloane, Jan 22 2018

Extensions

a(7)-a(50) from Charlie Neder, Apr 22 2019

Status

approved