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.

A217156 Number of perfect squared squares of order n up to symmetries of the square.

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, 30, 172, 541, 1372, 3949, 10209, 26234, 71892, 196357, 528866, 1420439, 3784262, 10012056, 26048712
Offset: 1

Views

Author

Geoffrey H. Morley, Sep 27 2012

Keywords

Comments

a(n) is the number of solutions to the classic problem of 'squaring the square' by n unequal squares. 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, and compound if it does.

Examples

			a(21) = 1 because there is a unique perfect squared square of order 21. A014530 gives the sizes of its constituent squares.
		

References

  • H. T. Croft, K. J. Falconer, and R. K. Guy, Unsolved Problems in Geometry, Springer-Verlag, 1991, section C2, pp. 81-83.
  • A. J. W. Duijvestijn, Fast calculation of inverse matrices occurring in squared rectangle calculation, Philips Res. Rep. 30 (1975), 329-339.
  • P. J. Federico, Squaring rectangles and squares: A historical review with annotated bibliography, in Graph Theory and Related Topics, J. A. Bondy and U. S. R. Murty, eds., Academic Press, 1979, 173-196.
  • J. H. van Lint and R. M. Wilson, A course in combinatorics, Chapter 34 "Electrical networks and squared squares", pp. 449-460, Cambridge Univ. Press, 1992.
  • J. D. Skinner II, Squared Squares: Who's Who & What's What, published by the author, 1993.
  • I. Stewart, Squaring the Square, Scientific Amer., 277, July 1997, pp. 94-96.
  • W. T. Tutte, Squaring the Square, in M. Gardner's 'Mathematical Games' column in Scientific American 199, Nov. 1958, pp. 136-142, 166. Reprinted with addendum and bibliography in the US in M. Gardner, The 2nd Scientific American Book of Mathematical Puzzles & Diversions, Simon and Schuster, New York (1961), pp. 186-209, 250, and in the UK in M. Gardner, More Mathematical Puzzles and Diversions, Bell (1963) and Penguin Books (1966), pp. 146-164, 186-7.
  • W. T. Tutte, Graph theory as I have known it, Chapter 1 "Squaring the square", pp. 1-11, Clarendon Press, Oxford, 1998.

Crossrefs

Cf. A181735 (counts symmetries of any squared subrectangles as equivalent).

Formula

a(n) = A006983(n) + A217155(n).

Extensions

Added a(29) = 10209, Stuart E Anderson, Nov 30 2012
Added a(30) = 26234, Stuart E Anderson, May 26 2013
Added a(31) = 71892, a(32) = 196357, Stuart E Anderson, Sep 30 2013
Added a(33) = 528866, a(34) = 1420439, a(35) = 3784262, due to enumeration completed by Jim Williams in 2014 and 2016. Stuart E Anderson, May 02 2016
a(36) and a(37) completed by Jim Williams in 2016 to 2018, added by Stuart E Anderson, Oct 28 2020

A181735 Number of perfect squared squares of order n up to symmetries of the square and of its squared subrectangles, if any.

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, 27, 162, 457, 1198, 3144, 8313, 21507, 57329, 152102, 400610, 1053254, 2750411, 7140575, 18326660
Offset: 1

Views

Author

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. A squared rectangle is simple if it does not contain a smaller squared rectangle, and compound if it does. - Geoffrey H. Morley, Oct 17 2012

Examples

			From _Geoffrey H. Morley_, Oct 17 2012 (Start):
a(21) = 1 because there is a unique perfect squared square of order 21. A014530 gives the sizes of its constituent squares.
a(24) = 27 because there are A217156(24) = 30 perfect squared squares of order 24 but four of them differ only in the symmetries of a squared subrectangle. (End)
		

References

  • See A217156 for further references and links.
  • J. D. Skinner II, Squared Squares: Who's Who & What's What, published by the author, 1993.

Crossrefs

Cf. A217156 (counts symmetries of any subrectangles as distinct).

Formula

a(n) = A006983(n) + A181340(n). - Geoffrey H. Morley, Oct 17 2012

Extensions

Corrected last term to 3144 to reflect correction to 143 of last order 28 compound squares term in A181340.
Added more clarification in comments on definition of a perfect squared square. - Stuart E Anderson, May 23 2012
Definition corrected and offset changed to 1 by Geoffrey H. Morley, Oct 17 2012
a(29) added by Stuart E Anderson, Dec 01 2012
a(30) added by Stuart E Anderson, May 26 2013
a(31) and a(32) added by Stuart E Anderson, Sep 30 2013
a(33), a(34) and a(35) added after enumeration by Jim Williams, Stuart E Anderson, May 02 2016
a(36) and a(37) from Jim Williams, completed in 2018 to 2020, added by Stuart E Anderson, Oct 28 2020

A217154 Number of perfect squared rectangles of order n up to symmetries of the rectangle.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 2, 14, 62, 235, 821, 2868, 10193, 36404, 130174, 466913, 1681999, 6083873
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.
A squared rectangle is simple if it does not contain a smaller squared rectangle, compound if it does, and trivially compound if a constituent square has the same side length as a side of the squared rectangle under consideration.

Examples

			a(10) = 14 comprises the A002839(10) = 6 simple perfect squared rectangles (SPSRs) of order 10 and the 8 trivially compound perfect squared rectangles which each comprises one of the two order 9 SPSRs and one other square.
		

References

  • See crossrefs for references and links.

Crossrefs

Cf. A110148 (counts symmetries of any squared subrectangles as equivalent).

Formula

a(n) = A002839(n) + A217153(n) + A217375(n).
a(n) >= 2*a(n-1) + A002839(n) + 2*A002839(n-1) + A217153(n) + 2*A217153(n-1), with equality for n<19.

Extensions

a(19) and a(20) corrected by Geoffrey H. Morley, Oct 12 2012

A217152 Number of nontrivially compound perfect squared rectangles of order n up to symmetries of the rectangle and its subrectangles.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 9, 46, 191, 781, 3161, 15002
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.
A squared rectangle is simple if it does not contain a smaller squared rectangle, compound if it does, and trivially compound if a constituent square has the same side length as a side of the squared rectangle under consideration.

Crossrefs

Cf. A217153 (counts symmetries of subrectangles as distinct).

Extensions

a(18) and a(19) added by Geoffrey H. Morley, Oct 12 2012

A217374 Number of trivially compound perfect squared rectangles of order n up to symmetries of the rectangle and its subrectangles.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 16, 60, 194, 622, 2128, 7438, 25852, 90266, 317350, 1127800
Offset: 1

Views

Author

Geoffrey H. Morley, Oct 02 2012

Keywords

Comments

A squared rectangle 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, compound if it does, and trivially compound if a constituent square has the same side length as a side of the squared rectangle under consideration.

Crossrefs

Cf. A217375 (counts symmetries of squared subrectangles as distinct).
Cf. A110148.

Formula

a(n) = a(n-1) + 2*A002839(n-1) + 2*A217152(n-1).

Extensions

a(20) corrected by Geoffrey H. Morley, Oct 12 2012
Showing 1-5 of 5 results.