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.

A333294 Main diagonal of triangle in A333282.

Original entry on oeis.org

4, 56, 624, 3288, 16912, 51864, 164692, 422792, 1023416, 2101272, 4387296, 8214688, 15485996
Offset: 1

Views

Author

Keywords

Comments

Triangle gives number of nodes in graph LC(n,n) in the notation of Blomberg-Shannon-Sloane (2020).
See A333282 for other images.

Crossrefs

Cf. A333282.

Extensions

More terms from Scott R. Shannon, May 26 2021

A333519 Number of regions in a polygon whose boundary consists of n+2 equally spaced points around a semicircle and n+2 equally spaced points along the diameter (a total of 2n+2 points). See Comments for precise definition.

Original entry on oeis.org

0, 2, 13, 48, 141, 312, 652, 1160, 1978, 3106, 4775, 6826, 9803, 13328, 17904, 23536, 30652, 38640, 48945, 60300, 74248, 89892, 108768, 128990, 153826, 180206, 211483, 245000, 284375, 325140, 374450, 425312, 484168, 545938, 616981, 690132, 775077, 862220
Offset: 0

Views

Author

Keywords

Comments

A semicircular polygon with 2n+2 points is created by placing n+2 equally spaced vertices along the semicircle's arc (including the two end vertices). Also place n+2 equally spaced vertices along the diameter (again including the same two end vertices). Now connect every pair of vertices by a straight line segment. The sequence gives the number of regions in the resulting figure.

Crossrefs

Extensions

a(21) and beyond from Lars Blomberg, May 01 2020

A333283 Triangle read by rows: T(m,n) (m >= n >= 1) = number of edges formed by drawing the line segments connecting any two of the (m+1) X (n+1) lattice points in an m X n grid of squares and extending them to the boundary of the grid.

Original entry on oeis.org

8, 28, 92, 80, 320, 1028, 178, 716, 2348, 5512, 372, 1604, 5332, 12676, 28552, 654, 2834, 9404, 22238, 49928, 87540, 1124, 5008, 16696, 39496, 88540, 156504, 279100, 1782, 7874, 26458, 62818, 141386, 251136, 447870
Offset: 1

Views

Author

Keywords

Comments

If we only joined pairs of the 2(m+n) boundary points, we would get A331454. If we did not extend the lines to the boundary of the grid, we would get A333278. (One of the links below shows the difference between the three definitions in the case m=3, n=2.)
See A333282 for a large number of colored illustrations.

Examples

			Triangle begins:
8,
28, 92,
80, 320, 1028,
178, 716, 2348, 5512,
372, 1604, 5332, 12676, 28552,
654, 2834, 9404, 22238, 49928, 87540,
1124, 5008, 16696, 39496, 88540, 156504, 279100,
1782, 7874, 26458, 62818, 141386, 251136, 447870, ...
...
T(7,7) corrected Mar 19 2020
		

Crossrefs

Cf. A288187, A331452, A333278, A331454, A333282 (regions), A333284 (vertices). Column 1 is A331757.

Extensions

More terms and corrections from Scott R. Shannon, Mar 21 2020

A333284 Triangle read by rows: T(m,n) (m >= n >= 1) = number of vertices formed by drawing the line segments connecting any two of the (m+1) X (n+1) lattice points in an m X n grid of squares and extending them to the boundary of the grid.

Original entry on oeis.org

5, 13, 37, 35, 129, 405, 75, 289, 933, 2225, 159, 663, 2155, 5157, 11641, 275, 1163, 3793, 9051, 20341, 35677, 477, 2069, 6771, 16129, 36173, 63987, 114409, 755, 3251, 10727, 25635, 57759, 102845, 183961
Offset: 1

Views

Author

Keywords

Comments

If we only joined pairs of the 2(m+n) boundary points, we would get A331453. If we did not extend the lines to the boundary of the grid, we would get A288180. (One of the links below shows the difference between the three definitions in the case m=3, n=2.)
See A333282 for a large number of colored illustrations.

Examples

			Triangle begins:
5,
13, 37,
35, 129, 405,
75, 289, 933, 2225,
159, 663, 2155, 5157, 11641,
275, 1163, 3793, 9051, 20341, 35677,
477, 2069, 6771, 16129, 36173, 63987, 114409,
755, 3251, 10727, 25635, 57759, 102845, 183961, ...
...
T(7,7) corrected Mar 19 2020
		

Crossrefs

Cf. A288187, A331452, A288180, A331453, A333282 (regions), A333283 (edges). Column 1 is A331755. The main diagonal is A333285.

Extensions

More terms and corrections from Scott R. Shannon, Mar 21 2020

A333285 The main diagonal of the triangular array A333284.

Original entry on oeis.org

5, 37, 405, 2225, 11641, 35677, 114409, 295701, 718469, 1475709, 3093025, 5771929, 10895273, 18785841, 31414269, 50274501, 81288641, 124066161, 190860537, 282399889, 411505049, 580614301, 824814797, 1138709849, 1570665877, 2115178249, 2833746309, 3732420861, 4937226173
Offset: 1

Views

Author

Keywords

Comments

See A333282, A333283, and A333284 for further information, illustrations, etc.

Crossrefs

Showing 1-5 of 5 results.