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 1-4 of 4 results.

A331908 The number of regions inside a hexagram formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.

Original entry on oeis.org

168, 3588, 20424, 73860, 189468, 402216, 782808, 1385040, 2214108, 3423840, 5196312, 7218552, 10353432, 13823772, 18047124, 24083736, 31051152, 38334972, 48877440, 59201544, 72052956, 88004184, 106601088, 124009020
Offset: 1

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Comments

The terms are from numeric computation - no formula for a(n) is currently known.

Crossrefs

Cf. A331909 (n-gons), A333116 (vertices), A333049 (edges), A007678, A092867, A331452, A331906.

Extensions

a(6)-a(24) from Lars Blomberg, May 10 2020

A331909 Triangle read by rows: Take a hexagram with all diagonals drawn, as in A331908. Then T(n,k) = number of k-sided polygons in that figure for k = 3, 4, ..., n+5.

Original entry on oeis.org

132, 36, 0, 0, 2052, 1188, 324, 24, 0, 10440, 7956, 1728, 300, 0, 0, 33672, 28812, 9276, 1836, 228, 24, 12, 83040, 75276, 24948, 5436, 708, 60, 0, 0, 172140, 162060, 54732, 11280, 1836, 168, 0, 0, 0, 322284, 315492, 114624, 25980, 3948, 456, 24, 0, 0, 0
Offset: 1

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Comments

See the links in A331908 for images of the hexagrams.

Examples

			A hexagram with no other points along its edges, n = 1, contains 132 triangles, 36 quadrilaterals and no other n-gons, so the first row is [132,36,0,0]. A hexagram with 1 point dividing its edges, n = 2, contains 2052 triangles, 1188 quadrilaterals, 324 pentagons, 24 hexagons and no other n-gons, so the second row is [2052,1188,324,24,0].
Triangle begins:
  132, 36, 0, 0
  2052, 1188, 324, 24, 0
  10440, 7956, 1728, 300, 0, 0
  33672, 28812, 9276, 1836, 228, 24, 12
  83040, 75276, 24948, 5436, 708, 60, 0, 0
The row sums are A331908.
		

Crossrefs

Cf. A331908 (regions), A333116 (vertices), A333049 (edges), A007678, A092867, A331452, A331906.

Extensions

a(31) and beyond from Lars Blomberg, May 10 2020

A333049 The number of edges inside a hexagram formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.

Original entry on oeis.org

276, 6348, 36810, 137802, 356538, 760134, 1494702, 2668458, 4254294, 6597690, 10105662, 13949346, 20222142, 26925654, 35032086, 47139258, 60947286, 74831682, 96101142, 115904808, 141052560, 172931484, 210293622, 243217686
Offset: 1

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Author

Keywords

Comments

See the links in A331908 for images of the hexagrams.

Crossrefs

Cf. A331908 (regions), A331909 (n-gons), A333116 (vertices),

Extensions

a(6)-a(24) from Lars Blomberg, May 10 2020

A338003 The number of vertices in a 4-pointed star formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.

Original entry on oeis.org

37, 653, 5517, 17153, 50349, 97037, 204329, 330613, 571021, 835713, 1298533, 1764125
Offset: 1

Views

Author

Keywords

Comments

See A338002 for a definition of the star and images for the number of regions.

Crossrefs

Cf. A338002 (number of regions), A092866, A332599, A007569, A333117, A333116.

Extensions

a(8)-a(12) from Lars Blomberg, Apr 08 2021
Showing 1-4 of 4 results.