1,2

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!

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

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

Cf. A170906, A169757, A169758, A163862 (values at powers of 2).

Sequence in context: A312218 A265382 A056738 * A143978 A071994 A023661

Adjacent sequences: A170904 A170905 A170906 * A170908 A170909 A170910

nonn

N. J. A. Sloane, Jan 24 2010

More terms from R. J. Mathar, Jan 28 2010

approved