OFFSET
1,2
COMMENTS
Total number of cells that get turned ON in the n-th 30-60-90 triangle of hexagons described in A170906.
I wish I had a recurrence for this sequence!
LINKS
David Applegate, Table of n, a(n) for n = 1..5989
David Applegate, Omar E. Pol and N. J. A. Sloane, The Toothpick Sequence and Other Sequences from Cellular Automata, Congressus Numerantium, Vol. 206 (2010), 157-191. [There is a typo in Theorem 6: (13) should read u(n) = 4.3^(wt(n-1)-1) for n >= 2.]
N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 24 2010
EXTENSIONS
More terms from R. J. Mathar, Jan 28 2010
STATUS
approved