A160406 -id:A160406 - cp's OEIS frontend

A161910 Y-toothpick sequence starting at the corner of an infinite hexagon from which protrudes a half toothpick with an angle = Pi/6.

0, 1, 2, 5, 6, 9, 12, 19, 22, 25, 28, 35, 40, 47, 56, 73

Offset: 0

Omar E. Pol, Jun 21 2009

The sequence gives the number of Y-toothpicks in the structure after n rounds. A160123 (the first differences) gives the number added at the n-th round.

See the entries A160120, A161830 and A161426 for more information about Y-toothpick sequences.

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

Cf. A160120, A160121, A160123, A160406, A161426, A161830, A161831.

a(n) = (A160120(n+1)-1)/3.

A160419 a(n) = A160409(n+2)/2.

Original entry on oeis.org

1, 2, 2, 2, 2, 2, 4, 8

Offset: 1

Omar E. Pol, May 23 2009

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

Cf. A139250, A139251, A160160, A160161, A160406, A160407, A160408, A160409, A160418.

cp's OEIS Frontend

A161910 Y-toothpick sequence starting at the corner of an infinite hexagon from which protrudes a half toothpick with an angle = Pi/6.

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