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 1-10 of 10 results.

A337267 A335703(2n).

Original entry on oeis.org

1, 3, 9, 30, 95, 326, 1195, 4478, 17251, 67326, 266331, 1058146, 4216075, 16808282, 67130923, 268281390, 1072424939
Offset: 0

Views

Author

Rémy Sigrist and N. J. A. Sloane, Aug 26 2020

Keywords

Crossrefs

A337268 a(n) = A335703(2n+1).

Original entry on oeis.org

2, 5, 16, 52, 174, 618, 2300, 8764, 34038, 133858, 530876, 2112904, 8417830, 33592910, 134211556, 536403988, 2144322638
Offset: 0

Views

Author

Rémy Sigrist and N. J. A. Sloane, Aug 26 2020

Keywords

Crossrefs

A337269 A335703(4n).

Original entry on oeis.org

1, 9, 95, 1195, 17251, 266331, 4216075, 67130923, 1072424939
Offset: 0

Views

Author

Rémy Sigrist and N. J. A. Sloane, Aug 26 2020

Keywords

Comments

In theory this should be easier to analyze than A335703, since the construction follows a cycle of four steps.

Crossrefs

A337270 Number of regions formed at generation n when the Conant "warp and woof" construction is applied to the base and left side of an equilateral triangle.

Original entry on oeis.org

1, 2, 3, 5, 7, 13, 20, 36, 57, 108, 185, 355, 637, 1246, 2344, 4595, 8895, 17532, 34592, 68287, 136053, 269046, 539516, 1068111, 2147477, 4254870, 8567392, 16982215, 34213477, 67850054, 136710948, 271162515, 546323617, 1083843471
Offset: 0

Views

Author

Rémy Sigrist and N. J. A. Sloane, Aug 27 2020

Keywords

Comments

This sequence completes a set of four. (1) The original Conant warp and woof construction used dissection lines that alternated between the base and left side of a square (see A328078).
(2) Robert Fathauer observed that if the construction starts with an equilateral triangle, and the dissection lines start from each of the three sides in rotation, the resulting structure in generation 3n converges to the Sierpinski Gasket fractal (see A329774).
(3) If the construction is applied to a square, and the dissection lines start from each of the four sides in rotation, we obtain the structures shown in A335703. To our surprise, these is no apparent fractal structure.
(4) The remaining case, an equilateral triangle with the dissection lines alternating between the base and the left side, is the subject of the present sequence.

Crossrefs

A334630 Number of regions after generation n of Conant's dissection of a square when dissected with diagonal lines.

Original entry on oeis.org

1, 2, 3, 5, 7, 12, 20, 35, 61, 106, 187, 347, 642, 1223, 2348, 4554, 8949, 17486, 34736, 68220, 135861, 268434, 535977, 1063240, 2125421, 4228727, 8457226, 16860125, 33723361, 67309114, 134632684, 268894671, 537869772, 1074864547
Offset: 0

Views

Author

Scott R. Shannon, Sep 10 2020

Keywords

Comments

See A328078 for details of the iterative dissection. Here a similar procedure is performed on a square except that diagonal lines are used. The first step cuts from the lower left corner to the upper right corner, forming two regions for generation 1. The next generation cuts from the lower right corner to the upper left corner, creating three regions in all. From then on each generation alternates from cutting from the left and bottom edge (towards the top and right edge), to cutting from the bottom and right edge (towards the left and top edge).
Like the standard orthogonal lines dissection of A328078 no obvious repetitive pattern appears as the generations increases. However from about n=17 the images, see attached links, show lines of higher density crossings, the first about one quarter of the way up from the bottom. Underneath this are three similar smaller separate lines, and underneath those additional lines. Interestingly the largest top line appears to be slightly off-center and shifted to the left.
The author thanks Rémy Sigrist whose code given in A328078 was modified to generate the larger values of this sequence.

Crossrefs

A335093 Number of regions after generation n of Conant's dissection of a square when dissected with diagonal lines and where the starting pair of edges rotates counterclockwise around the square.

Original entry on oeis.org

1, 2, 3, 5, 7, 12, 18, 33, 57, 105, 186, 348, 648, 1226, 2347, 4535, 8840, 17386, 34229, 67708, 134210, 266779, 531277, 1058724, 2112238, 4215738, 8421830, 16822772, 33624420, 67204921, 134363536, 268636845, 537171420, 1074115099
Offset: 0

Views

Author

Scott R. Shannon, Sep 12 2020

Keywords

Comments

This is a variation of A334630 where the pair of edges where the dissection begins starts at the left and bottom edges of the square and then proceeds counterclockwise around the square, the dissection halving in size after every two steps.
For the first generation a single dissection line is drawn from the bottom left to the top right corner of the square. For the second generation a single line is drawn from the bottom right corner toward to top left corner. For the third generation the dissection size halves and moves counterclockwise so now two lines are drawn from the top edge toward the left edge and also two lines from the right edge toward the bottom edge. For the fourth generation two lines are drawn from the top edge toward the right edge and two lines from the left edge toward the bottom edge. The dissection again moves counterclockwise and halves in size so now starts at the left and bottom edge again, and for the fifth generation draws four lines on each edge. The sequence gives the number of regions in the resulting dissection after generation n.
Like the standard orthogonal lines dissection of A328078 no obvious repetitive pattern appears as the generations increases. But unlike A334630 there appears to be no high density horizontal lines appearing in the resulting dissection, see the linked images.
The author thanks Rémy Sigrist whose code given in A328078 was modified to generate the larger values of this sequence.

Crossrefs

A337675 Number of regions after generation n of Conant's dissection of a square where the starting edge rotates clockwise around the square and the dissection halves in size after every generation.

Original entry on oeis.org

1, 2, 4, 10, 30, 78, 302, 1038, 4174, 14670, 60238, 237902, 955726, 3704142, 14935374, 60015950, 239994190, 951256398
Offset: 0

Views

Author

Scott R. Shannon, Sep 15 2020

Keywords

Comments

This is a variation of A335703 where the edge where the dissections begin starts at the bottom edge of the square and then proceeds clockwise around the square after each generation. However unlike A335703, where the dissection halves in size after every two generations, here it halves in size after every single generation. The resulting pattern, which resembles images of a printed circuit for large n, stays fairly constant while the internal regions are cut into smaller rectangles and squares after each generation.
The author thanks Rémy Sigrist whose code given in A328078 was modified to generate the larger values of this sequence.

Crossrefs

A335628 Number of regions after generation n of Conant's dissection of a square when dissected with both orthogonal and diagonal lines and where the starting edges rotate clockwise around the square and the dissection halves in size every second generation.

Original entry on oeis.org

1, 2, 3, 6, 11, 20, 37, 68, 123, 232, 457, 879, 1679, 3269, 6478, 12799, 25272, 50127, 99888, 198867, 396267, 791069, 1580460, 3156095, 6305694, 12606152, 25205005, 50388077
Offset: 0

Views

Author

Scott R. Shannon, Oct 02 2020

Keywords

Comments

This is a variation of A328078 and A334630 where the square is dissected with both orthogonal and diagonal lines.
For the first generation, a single orthogonal dissection line is drawn from the bottom to the top edge of the square. For the second generation, a single diagonal line is drawn from the bottom left corner toward to top right corner. The edge where the dissections start now rotates clockwise around the square and the dissection size halves. For the third generation, two orthogonal dissection lines are drawn from the left edge toward the right edge. For the fourth generation, four diagonal lines, two from the left edge and two from the top edge, are drawn from the top-left corner toward the bottom right corner. The edge now rotates clockwise again and the dissection size halves. The sequences gives the number of regions in the resulting dissection after generation n.
The author thanks Rémy Sigrist whose code given in A328078 was modified to generate the larger values of this sequence.

Crossrefs

A335632 Number of regions after generation n of Conant's dissection of a square when dissected with both diagonal and orthogonal lines and where the starting edges rotate clockwise around the square and the dissection halves in size every second generation.

Original entry on oeis.org

1, 2, 3, 8, 11, 25, 37, 97, 142, 316, 463, 1150, 1747, 4298, 6599, 16641, 25800, 65025, 101027, 256245, 399972, 1017939, 1589375, 4048559, 6328766, 16148228, 25252615, 53243252
Offset: 0

Views

Author

Scott R. Shannon, Oct 03 2020

Keywords

Comments

This is a variation of A335628 where the same rules are applied but the first dissection is with a diagonal line from the lower left corner to the upper right corner, followed by dissection with an orthogonal line from the left edge. For further details see A335628.

Crossrefs

A337693 Number of regions after generation n of Conant's dissection of a square when dissected with diagonal lines and where the starting edges rotate counterclockwise around the square and the dissection halves in size after every generation.

Original entry on oeis.org

1, 2, 4, 9, 25, 61, 197, 597, 2165, 7861, 30549, 118869, 471765, 1873621, 7479637, 29864277, 119397205
Offset: 0

Views

Author

Scott R. Shannon, Sep 15 2020

Keywords

Comments

This is a variation of A335093 in which the edges where the diagonal dissections begin start at the left and bottom edge of the square and then proceeds counterclockwise around the square after each generation. However unlike A335093, where the dissection halves in size after every two generations, here it halves in size after every single generation. The resulting pattern for larger n shows vertical and horizontal lines of higher density crossings similar to those seen in A334630.
The author thanks Rémy Sigrist whose code given in A328078 was modified to generate the larger values of this sequence.

Crossrefs

Showing 1-10 of 10 results.