A169778 a(n) = ceiling(A170905/2).

0, 1, 1, 1, 2, 1, 2, 3, 4, 1, 2, 3, 5, 5, 4, 7, 8, 1, 2, 3, 5, 5, 5, 9, 13, 9, 4, 7, 12, 14, 10, 16, 16, 1, 2, 3, 5, 5, 5, 9, 13, 9, 5, 9, 15, 19, 17, 21, 29, 17, 4, 7, 12, 14, 14, 22, 34, 30, 14, 16, 28, 35, 25, 35, 32, 1, 2, 3, 5, 5, 5, 9, 13, 9, 5, 9, 15, 19, 17, 21

Offset: 0

Author

N. J. A. Sloane, May 08 2010

Keywords

• nonn
• tabf

Comments

The hexagon-based CA of A151723 has as symmetry group the dihedral group of order 12. Consider a one-twelfth slice; a(n) is the number of cells that are turned from OFF to ON at generation n.

Examples

			Illustration of generations 1 through 9:
.1
..2
...3
..4.4
.....5
..7.6.6
...7...7
..8.8.8.8
.........9
...
From _Omar E. Pol_, Feb 12 2013: (Start)
When written as a triangle from 1, the right border gives A011782 and row lengths give A011782.
1,
1,
1,2,
1,2,3,4,
1,2,3,5,5,4,7,8,
1,2,3,5,5,5,9,13,9,4,7,12,14,10,16,16,
1,2,3,5,5,5,9,13,9,5,9,15,19,17,21,29,17,4,7,12,14,14,22,34,30,14,16,28,35,25,35,32;
1,2,3,5,5,5,9,13,9,5,9,15,19,17,21,... (End)
		

Crossrefs

Cf. A151723, A151724, A170905.

Formula

A170905(n) = 2a(n) except A170905(1)=1.