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A255748 Total number of ON states after n generations of cellular automaton based on triangles in a 60-degree wedge (see Comments lines for definition). 3
1, 3, 4, 8, 11, 13, 14, 22, 29, 35, 40, 44, 47, 49, 50, 66, 81, 95, 108, 120, 131, 141, 150, 158, 165, 171, 176, 180, 183, 185, 186, 218, 249, 279, 308, 336, 363, 389, 414, 438, 461, 483, 504, 524, 543, 561, 578, 594, 609, 623, 636, 648, 659, 669, 678, 686, 693, 699, 704, 708, 711, 713, 714, 778, 841, 903, 964, 1024 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also partial sums of A080079.

In order to construct the structure we use the following rules:

On the infinite triangular grid we are in a 60-degree wedge with the vertex located on top of the wedge.

The nearest triangular cell to the vertex remains OFF.

At stage 1, we turn ON the cell whose base is adjacent to the previous OFF cell.

At stage n, in the n-th level of the structure, we turn ON k cells connected by their vertices with their bases up, where k = A080079(n).

The cells turned ON remain ON forever.

The structure seems to grow into the holes of a virtual Sierpiński's triangle (see example).

Note that this is also the structure in every one of the six wedges of the structure of A256266.

A080079 gives the number of cells turned ON at n-th stage.

LINKS

Table of n, a(n) for n=1..68.

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

Index entries for sequences related to cellular automata

FORMULA

a(n) = A256266(n)/6.

EXAMPLE

Illustration of initial terms:

-----------------------------------------------------------

n   A080079(n)   a(n)                  Diagram

-----------------------------------------------------------

.                                        / \

1       1         1                     / T \

2       2         3                    / T T \

3       1         4                   /   T   \

4       4         8                  / T T T T \

5       3        11                 /   T T T   \

6       2        13                /     T T     \

7       1        14               /       T       \

8       8        22              / T T T T T T T T \

9       7        29             /   T T T T T T T   \

10      6        35            /     T T T T T T     \

11      5        40           /       T T T T T       \

12      4        44          /         T T T T         \

13      3        47         /           T T T           \

14      2        49        /             T T             \

15      1        50       /               T               \

...

For n = 15 after 15 generations there are 50 ON cells in the structure, so a(15) = 50.

CROSSREFS

Cf. A047999, A001316, A080079, A139250, A169779, A169788, A170905, A233970, A256256, A256266.

Sequence in context: A243177 A113294 A169691 * A152412 A287404 A287388

Adjacent sequences:  A255745 A255746 A255747 * A255749 A255750 A255751

KEYWORD

nonn,look

AUTHOR

Omar E. Pol, Mar 30 2015

STATUS

approved

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Last modified October 15 04:33 EDT 2019. Contains 328026 sequences. (Running on oeis4.)