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.

Showing 1-3 of 3 results.

A161833 First differences of A161832.

Original entry on oeis.org

1, 1, 2, 1, 2, 2, 4, 2, 2, 2, 4, 3, 4, 5, 9, 5, 2
Offset: 1

Views

Author

Omar E. Pol, Jun 20 2009

Keywords

Comments

Number of Y-toothpicks added to the sieve at the n-th round.

Links

Crossrefs

Cf. A139251, A160121, A160407, A161830, A161831, A161832.

Formula

a(n) = A161831(n+1)/2.

A161831 First differences of A161830.

Original entry on oeis.org

1, 2, 2, 4, 2, 4, 4, 8, 4, 4, 4, 8, 6, 8, 10, 18, 10, 4
Offset: 1

Views

Author

Omar E. Pol, Jun 20 2009

Keywords

Comments

Number of Y-toothpicks added to the sieve at the n-th round.

Links

Crossrefs

Cf. A139250, A139251, A160121, A160407, A161830, A161832, A161833.

A161830 Y-toothpick triangle (see Comments lines for definition).

Original entry on oeis.org

0, 1, 3, 5, 9, 11, 15, 19, 27, 31, 35, 39, 47, 53, 61, 71, 89, 99, 103
Offset: 0

Views

Author

Omar E. Pol, Jun 20 2009

Keywords

Comments

Y-toothpick sequence starting at the corner of an infinite hexagon in which its vertex touch an endpoint of the initial Y-toothpick and the two other endpoints are equidistant from the nearest sides of the hexagon.
The sequence gives the number of Y-toothpicks in the structure after n rounds. A161831 (the first differences) gives the number added at the n-th round.
See the Y-toothpick sequence A160120 for more information about the recursive, fractal-like structure.

Links

Crossrefs

Cf. A139250, A160120, A160121, A160406, A160407, A161831, A161832, A161833.
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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