cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A160123 a(n) = A160121(n+1)/3.

Original entry on oeis.org

1, 1, 3, 1, 3, 3, 7, 3, 3, 3, 7, 5, 7, 9, 17, 9, 3, 3, 7, 5, 7, 9, 17, 11, 7, 9, 17, 17, 19, 23, 39, 27, 7, 3, 7, 5, 7, 9, 17, 11, 7, 9, 17, 17, 19, 23, 39, 29, 11, 9, 17, 17, 19, 25, 43, 39, 25, 23, 39, 45, 47, 57, 93, 77, 23, 3, 7, 5, 7, 9
Offset: 1

Views

Author

Omar E. Pol, May 02 2009, May 21 2010

Keywords

Comments

Also, first differences of A161910. [From Omar E. Pol, Jun 21 2009]

Examples

			Note that this can be written as a triangle:
1;
1;
3;
1,3;
3,7,3,3;
3,7,5,7,9,17,9,3;
3,7,5,7,9,17,11,7,9,17,17,19,23,39,27,7;
3,7,5,7,9,17,11,7,9,17,17,19,23,39,29,11,9,17,17,19,25,43,39,25,23,39,45,47,57,93,77,23;
3,7,5,7,9,...
		

Crossrefs

Y-toothpick sequence: A160120. Cf. A160121, A160122.
Cf. A139250, A139251. [From Omar E. Pol, Jun 16 2009]
Cf. A161831, A161427, A161910. [From Omar E. Pol, Jun 21 2009]

Extensions

More terms from Omar E. Pol, Jun 16 2009
Extended by R. J. Mathar, Feb 05 2010

A161426 Y-toothpick sequence starting at the outside corner of an infinite triangle-shaped polygon as the sieve of A160120 after 2^k rounds.

Original entry on oeis.org

0, 1, 4, 7, 14, 19, 26, 35, 52, 63, 70
Offset: 0

Views

Author

Omar E. Pol and David Applegate, Jun 20 2009

Keywords

Comments

The sequence gives the number of Y-toothpicks after n rounds. A161427 (the first differences) gives the number added at the n-th round.
See the entries A160120, A139250 and A153006 for more information.

Crossrefs

Showing 1-2 of 2 results.