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 11 results. Next

A006983 Number of simple perfect squared squares of order n up to symmetry.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 8, 12, 26, 160, 441, 1152, 3001, 7901, 20566, 54541, 144161, 378197, 990981, 2578081, 6674067, 17086918
Offset: 1

Views

Author

Keywords

Comments

A squared rectangle (which may be a square) is a rectangle dissected into a finite number of two or more squares. If no two squares have the same size, the squared rectangle is perfect. A squared rectangle is simple if it does not contain a smaller squared rectangle. The order of a squared rectangle is the number of constituent squares. - Geoffrey H. Morley, Oct 17 2012

References

  • J.-P. Delahaye, Les inattendus mathématiques, Belin-Pour la Science, Paris, 2004, pp. 95-96.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A129947, A217149, A228953 (related to sizes of the squares).
Cf. A349205, A349206, A349207, A349208, A349209, A349210 (related to ratios of element and square sizes).

Extensions

Leading term changed from 0 to 1, Apr 15 1996
More terms from Stuart E Anderson, May 08 2003, Nov 2010
Leading term changed back to 0, Dec 25 2010 (cf. A178688)
a(29) added by Stuart E Anderson, Aug 22 2010; contributors to a(29) include Ed Pegg Jr and Stephen Johnson
a(29) changed to 7901, identified a duplicate tiling in order 29. - Stuart E Anderson, Jan 07 2012
a(28) changed to 3000, identified a duplicate tiling in order 28. - Stuart E Anderson, Jan 14 2012
a(28) changed back to 3001 after a complete recount of order 28 SPSS recalculated from c-nets with cleansed data, established the correct total of 3001. - Stuart E Anderson, Jan 24 2012
Definition clarified by Geoffrey H. Morley, Oct 17 2012
a(30) added by Stuart E Anderson, Apr 10 2013
a(31), a(32) added by Stuart E Anderson, Sep 29 2013
a(33), a(34) and a(35) added by Stuart E Anderson, May 02 2016
Moved comments on orders 27 to 35 to a linked file. Stuart E Anderson, May 02 2016
a(36) and a(37) enumerated by Jim Williams, added by Stuart E Anderson, Jul 26 2020.

A217149 Largest possible side length for a perfect squared square of order n; or 0 if no such square exists.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 112, 192, 332, 479, 661, 825, 1179, 1544, 2134, 2710, 3641, 4988, 6391, 8430, 11216, 15039, 20242
Offset: 1

Views

Author

Geoffrey H. Morley, Sep 27 2012

Keywords

Comments

A squared rectangle (which may be a square) is a rectangle dissected into a finite number, two or more, of squares. If no two of these squares have the same size the squared rectangle is perfect. The order of a squared rectangle is the number of constituent squares. By convention the sides of the subsquares are integers with no common factor.
A squared rectangle is simple if it does not contain a smaller squared rectangle. Every perfect square with the largest known side length for each order up to 37 is simple.

Crossrefs

Extensions

a(29) from Stuart E Anderson added by Geoffrey H. Morley, Nov 23 2012
a(30), a(31), a(32) from Lorenz Milla and Stuart E Anderson, added by Stuart E Anderson, Oct 05 2013
For additional terms see the Ed Pegg link, also A006983. - N. J. A. Sloane, Jul 29 2020
a(33) to a(37) from J. B. Williams added by Stuart E Anderson, Oct 27 2020

A228953 The largest possible element size for each perfect squared square order, otherwise 0 if perfect squared squares do not exist in that order.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 50, 97, 134, 200, 343, 440, 590, 797, 1045, 1435, 1855, 2505, 3296, 4528, 5751, 7739, 10361
Offset: 1

Views

Author

Stuart E Anderson, Oct 06 2013

Keywords

Comments

A squared rectangle is a rectangle dissected into a finite number, two or more, of squares, called the elements of the dissection. If no two of these squares have the same size the squared rectangle is called perfect, otherwise it is imperfect. The order of a squared rectangle is the number of constituent squares. The case in which the squared rectangle is itself a square is called a squared square. The dissection is simple if it contains no smaller squared rectangle, otherwise it is compound. Every perfect square with the largest known element for each order up to 37 is simple.

Crossrefs

Extensions

More terms, a(33) to a(37), extracted from Jim Williams' discoveries, added by Stuart E Anderson, Nov 06 2020

A349205 a(n) is the side length (size) of the smallest element in a simple perfect squared square of order n such that the ratio of the size of the smallest element to the total size of the square assumes a maximum over all possible A006983(n) dissections of order n.

Original entry on oeis.org

2, 4, 2, 3, 12, 17, 48, 29, 62, 53, 64, 156, 70, 270, 257, 333, 716
Offset: 21

Views

Author

Hugo Pfoertner, Nov 22 2021

Keywords

Examples

			See Pfoertner link.
		

Crossrefs

A349206 gives the corresponding total sizes of those squares that lead to the maximum ratio.

A349206 a(n) is the side length of the simple perfect squared square of order n leading to a maximum of the ratio of the side length of its smallest element A349205(n) to its total side length.

Original entry on oeis.org

112, 192, 140, 120, 381, 544, 1032, 732, 1615, 1485, 1408, 3584, 1625, 6808, 6192, 7743, 16581
Offset: 21

Views

Author

Hugo Pfoertner, Nov 22 2021

Keywords

Examples

			See A349205.
		

Crossrefs

A349207 a(n) is the side length (size) of the smallest element in a simple perfect squared square of order n such that the ratio of the size of the smallest element to the size of the largest element of the square assumes a maximum over all possible A006983(n) dissections of order n.

Original entry on oeis.org

2, 4, 2, 3, 16, 17, 48, 29, 62, 69, 64, 88, 70, 111, 355, 333, 543
Offset: 21

Views

Author

Hugo Pfoertner, Nov 22 2021

Keywords

Examples

			See Pfoertner link.
		

Crossrefs

A349208 gives the corresponding sizes of the largest elements that lead to the maximum ratio.

A349209 a(n) is the maximum of the side lengths of the smallest elements of all simple perfect squared squares of order n.

Original entry on oeis.org

2, 4, 2, 8, 16, 20, 48, 48, 69, 74, 107, 158, 177, 270, 355, 519, 716
Offset: 21

Views

Author

Hugo Pfoertner, Nov 17 2021

Keywords

Examples

			See linked illustrations.
		

Crossrefs

A349210 a(n) is the minimum of the side lengths of the largest elements of all simple perfect squared squares of order n.

Original entry on oeis.org

50, 55, 44, 47, 74, 78, 81, 77, 99, 77, 87, 80, 94, 79, 89, 96, 93
Offset: 21

Views

Author

Hugo Pfoertner, Nov 17 2021

Keywords

Examples

			See linked illustrations.
		

Crossrefs

A349208 a(n) is the largest side length (size) of an element of the simple perfect squared square of order n leading to a maximum of the ratio of the size of its smallest element A349207(n) to the size of its largest element.

Original entry on oeis.org

50, 86, 60, 47, 195, 202, 457, 304, 591, 698, 520, 769, 549, 860, 3276, 2456, 4098
Offset: 21

Views

Author

Hugo Pfoertner, Nov 22 2021

Keywords

Examples

			See A349207.
		

Crossrefs

A217148 Smallest possible side length for a perfect squared square of order n; or 0 if no such square exists.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 112, 110, 110, 120, 147, 212, 180, 201, 221, 201, 215, 185, 233, 218, 225, 253, 237
Offset: 1

Views

Author

Geoffrey H. Morley, Sep 27 2012

Keywords

Comments

It is not known whether this sequence is the same as sequence A129947. It may be that A129947(33) = 246 and A217148(33) = 234. - Geoffrey H. Morley, Jan 10 2013
A squared rectangle (which may be a square) is a rectangle dissected into a finite number, two or more, of squares. If no two of these squares have the same size the squared rectangle is perfect. The order of a squared rectangle is the number of constituent squares.
A squared rectangle is simple if it does not contain a smaller squared rectangle.
The upper bounds shown below for 38 and 40-44 are from J. B. Williams. Those for n = 39 and 45-47 are from Gambini's thesis. - Geoffrey H. Morley, Mar 08 2013
======================================
Upper bounds for a(n) for n = 31 to 59
======================================
| +0 +1 +2 +3 +4 +5 +6 +7 +8 +9
======================================================
30 | - - - - - - - - 352 360
40 | 328 336 360 413 425 543 601 691 550 583
50 | 644 636 584 685 657 631 751 742 780 958
======================================================
The sequence A129947 has identical terms to A217148 (so far), however they are different as A129947 refers to simple perfect squared squares (SPSSs), while A217148 refers to SPSSs and compound perfect squared squares (CPSSs). The simples and compounds together are referred to as perfect squared squares (PSSs). So far it has been observed that all the smallest side lengths belong to SPSSs only. - Stuart E Anderson, Oct 27 2020

Crossrefs

Extensions

a(29) from Stuart E Anderson added by Geoffrey H. Morley, Nov 23 2012
a(30) from Stuart E Anderson and Lorenz Milla added by Geoffrey H. Morley, Jun 15 2013
a(31) and a(32) from Lorenz Milla and Stuart E Anderson, Oct 05 2013
For additional terms see the Ed Pegg link, also A006983. - N. J. A. Sloane, Jul 29 2020
a(33) to a(37) from J. B. Williams added by Stuart E Anderson, Oct 27 2020
Showing 1-10 of 11 results. Next