A169779 Partial sums of A170898.

1, 2, 5, 6, 9, 14, 21, 22, 25, 30, 39, 48, 55, 68, 83, 84, 87, 92, 101, 110, 119, 136, 161, 178, 185, 198, 221, 248, 267, 298, 329, 330, 333, 338, 347, 356, 365, 382, 407, 424, 433, 450, 479, 516, 549, 590, 647, 680, 687, 700, 723, 750, 777, 820, 887, 946, 973, 1004, 1059

Offset: 0

Author

N. J. A. Sloane, May 10 2010

Keywords

• nonn

Comments

On the hexagonal grid consider an infinite 60-degree wedge. A cell is turned ON if exactly one of its six neighbors is ON. We start with a single ON cell. An ON cell remains ON forever. The sequence counts the total number of ON states after n generations. The structure is also the tree that arises from one of the six spokes of the structure of A151723. For n >> 1 the structure looks like a quadrilateral formed by two scalene right triangles which are joined at their hypotenuses. - Omar E. Pol, Mar 06 2013

Links

• N. J. A. Sloane, Table of n, a(n) for n = 0..1023
• N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
• Index entries for sequences related to cellular automata

Crossrefs

Cf. A151723, A169780.

Formula

a(n) = (A151723(n+2) - 1)/6. - Omar E. Pol, Mar 06 2013