A170926 Total number of squares and rectangles at the n-th stage in the corner toothpick structure (see A152890, A153006).

0, 0, 1, 3, 4, 5, 10, 17, 20, 21, 25, 30, 33, 40, 58, 77, 84, 85, 89, 94, 97, 104, 121, 138, 145, 151, 164, 177, 190, 222, 278, 325, 340, 341, 345, 350, 353, 360, 377, 394, 401, 407, 420, 433, 446, 478, 533, 578, 593, 599, 612, 625, 638, 669, 720, 761, 781, 806, 845, 884, 942

Offset

0,4

Links

Table of n, a(n) for n=0..60.

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

Formula

a(2^k) = (4^k-4)/3 for k >= 2. - N. J. A. Sloane, Feb 13 2010.

Crossrefs

Partial sums of A168131.

Sequence in context: A058615 A082612 A339569 * A122413 A297661 A342333

Adjacent sequences: A170923 A170924 A170925 * A170927 A170928 A170929

Keyword

nonn

Author

Omar E. Pol, Jan 18 2010

Extensions

Edited and extended by N. J. A. Sloane, Feb 01 2010

Status

approved