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 1-5 of 5 results.

A359935 Irregular table read by rows: T(n,k) is the number of k-gons, k>=2, among all distinct circles that can be constructed from an n x n square grid of points using only a compass.

Original entry on oeis.org

0, 16, 30, 0, 412, 341, 60, 20, 4, 0, 3464, 3534, 928, 212, 48, 12, 0, 16936, 19861, 5252, 1056, 88, 52, 8, 0, 63712, 77394, 20480, 4820, 612, 108, 20, 12, 4, 202904, 244013, 71244, 14968, 1852, 472, 80, 32, 4
Offset: 2

Views

Author

Scott R. Shannon, Jan 21 2023

Keywords

Comments

A circle is constructed for every pair of the n x n points, the first point defines the circle's center while the second the radius distance. The number of distinct circles constructed from the n x n points is A359931(n).
See A359932 and A359933 for images of the circles.
The first occurrence of a 2-gon is when n = 7. Assuming the grid points are separated by 1 unit, in the first quadrant this region has endpoints (6,7) and (7,6) - an equivalent region is in each of the three other quadrants. Its arcs are from two circles, one with center at (2,2) going through point (-2,-3) while the other has center (3,3) going through point (0,-1). See the attached image.

Examples

			The table begins:
0, 16, 30;
0, 412, 341, 60, 20, 4;
0, 3464, 3534, 928, 212, 48, 12;
0, 16936, 19861, 5252, 1056, 88, 52, 8;
0, 63712, 77394, 20480, 4820, 612, 108, 20, 12;
4, 202904, 244013, 71244, 14968, 1852, 472, 80, 32, 4;
.
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Crossrefs

Cf. A359932 (vertices), A359933 (regions), A359934 (edges), A359931 (distinct circles), A359862, A359258.

Formula

Sum of row n = A359933(n).

A361623 Irregular table read by rows: T(n,k) is the number of k-gons, k>=2, among all distinct circles that can be constructed from a point on the origin and n equally spaced points on each of the +x,-x,+y,-y coordinates axes using only a compass.

Original entry on oeis.org

0, 40, 60, 12, 0, 484, 583, 160, 28, 8, 0, 2196, 2416, 804, 104, 28, 0, 5676, 6616, 2184, 460, 40, 8, 13456, 16936, 5236, 1340, 104, 12, 4, 27512, 35032, 11796, 2400, 320, 28, 0, 4, 0, 50688, 65044, 22536, 4632, 584, 60, 12, 4, 8, 84300, 105860, 38024, 8124, 1080, 108
Offset: 1

Views

Author

Scott R. Shannon, Mar 18 2023

Keywords

Comments

A circle is constructed for every pair of the 1 + 4n points, the first point defines the circle's center while the second the radius distance. The number of distinct circles constructed from the points is A361622(n).
See A354605 and A353782 for images of the vertices and regions.

Examples

			The table begins:
 0, 40, 60, 12;
 0, 484, 583, 160, 28, 8;
 0, 2196, 2416, 804, 104, 28;
 0, 5676, 6616, 2184, 460, 40;
 8, 13456, 16936, 5236, 1340, 104, 12;
 4, 27512, 35032, 11796, 2400, 320, 28, 0, 4;
 0, 50688, 65044, 22536, 4632, 584, 60, 12, 4;
 8, 84300, 105860, 38024, 8124, 1080, 108;
.
.
		

Crossrefs

Cf. A354605 (vertices), A353782 (regions), A356358 (edges), A361622 (distinct circles), A359935, A359862, A359258, A359619, A359061.

Formula

Sum of row n = A353782(n).

A359859 Number of vertices among all distinct circles that can be constructed from a 2 x n square grid of points using only a compass.

Original entry on oeis.org

2, 40, 190, 740, 1824, 3956, 7314, 12956, 20684, 32276, 47348, 68516, 94550, 128780, 170106, 222252, 283418, 358756, 445534, 550868, 670358, 811556, 970740, 1157168, 1363700, 1601384, 1864524, 2164668, 2493136, 2865176, 3269606, 3724112, 4215536, 4762284, 5353050
Offset: 1

Views

Author

Scott R. Shannon, Jan 16 2023

Keywords

Comments

A circle is constructed for every pair of the 2 x n points, the first point defines the circle's center while the second the radius distance. The number of distinct circles constructed from the 2 x n points is conjectured to be 4*A001859(n-1).
No formula for a(n) is known.

Crossrefs

Cf. A359860 (regions), A359861 (edges), A359862 (k-gons), A001859, A359252.

Formula

a(n) = A359861(n) - A359860(n) + 1 by Euler's formula.

Extensions

a(19)-a(35) from Lucas A. Brown, Oct 11 2024

A359860 Number of regions among all distinct circles that can be constructed from a 2 X n square grid of points using only a compass.

Original entry on oeis.org

3, 45, 231, 865, 2081, 4489, 8211, 14401, 22857, 35445, 51741, 74397, 102271, 138801, 182739, 238181, 303175, 383097, 474995, 586021, 712003, 860829, 1028225, 1223773, 1440593, 1689993, 1965525, 2279509, 2622993, 3011405, 3433615, 3907241, 4419261, 4988781, 5603271
Offset: 1

Views

Author

Scott R. Shannon, Jan 16 2023

Keywords

Comments

See A359859 for further details. No formula for a(n) is known.

Crossrefs

Cf. A359859 (vertices), A359861 (edges), A359862 (k-gons), A001859, A359253.

Formula

a(n) = A359861(n) - A359859(n) + 1 by Euler's formula.

Extensions

a(19)-a(35) from Lucas A. Brown, Oct 11 2024

A359861 Number of edges among all distinct circles that can be constructed from a 2 X n square grid of points using only a compass.

Original entry on oeis.org

4, 84, 420, 1604, 3904, 8444, 15524, 27356, 43540, 67720, 99088, 142912, 196820, 267580, 352844, 460432, 586592, 741852, 920528, 1136888, 1382360, 1672384, 1998964, 2380940, 2804292, 3291376, 3830048, 4444176, 5116128, 5876580, 6703220, 7631352, 8634796, 9751064, 10956320
Offset: 1

Views

Author

Scott R. Shannon, Jan 16 2023

Keywords

Comments

See A359859 and A359860 for further details and images of the circles. No formula for a(n) is known.

Examples

			a(n) = A359859(n) + A359860(n) - 1 by Euler's formula.
		

Crossrefs

Cf. A359859 (vertices), A359860 (regions), A359862 (k-gons), A001859, A359254.

Extensions

a(19)-a(35) from Lucas A. Brown, Oct 11 2024
Showing 1-5 of 5 results.