A170907 Row sums in triangle A170906.

1, 4, 8, 13, 20, 28, 37, 47, 59, 73, 87, 101, 118, 137, 156, 176, 198, 223, 248, 271, 299, 328, 357, 386, 418, 454, 489, 522, 558, 598, 638, 678, 720, 766, 812, 858, 907, 956, 1004, 1048, 1104, 1161, 1217, 1268, 1325, 1386, 1446, 1505, 1567, 1635, 1703, 1765

Offset: 1

Author

N. J. A. Sloane, Jan 24 2010

Keywords

• nonn

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

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

Extensions

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