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 1-3 of 3 results.

A006052 Number of magic squares of order n composed of the numbers from 1 to n^2, counted up to rotations and reflections.

Original entry on oeis.org

1, 0, 1, 880, 275305224, 17753889197660635632
Offset: 1

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Author

Keywords

Comments

a(4) computed by Frenicle de Bessy (1605? - 1675), published in 1693. The article mentions the 880 squares and considers also 5*5, 6*6, 8*8, and other squares. - Paul Curtz, Jul 13 and Aug 12 2011
a(5) computed by Richard C. Schroeppel in 1973.
According to Pinn and Wieczerkowski, a(6) = (0.17745 +- 0.00016) * 10^20. - R. K. Guy, May 01 2004
a(6) computed by Hidetoshi Mino in 2024 - Hidetoshi Mino, May 31 2024

Examples

			An illustration of the unique (up to rotations and reflections) magic square of order 3:
  +---+---+---+
  | 2 | 7 | 6 |
  +---+---+---+
  | 9 | 5 | 1 |
  +---+---+---+
  | 4 | 3 | 8 |
  +---+---+---+
		

References

  • E. R. Berlekamp, J. H. Conway and R. K. Guy, Winning Ways, Vol. II, pp. 778-783 gives the 880 4 X 4 squares.
  • M. Gardner, Mathematical Games, Sci. Amer. Vol. 249 (No. 1, 1976), p. 118.
  • M. Gardner, Time Travel and Other Mathematical Bewilderments. Freeman, NY, 1988, p. 216.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Extensions

Definition corrected by Max Alekseyev, Dec 25 2015
a(6) from Hidetoshi Mino, Jul 17 2023
Incorrect a(6) removed by Hidetoshi Mino, Sep 07 2023
a(6) from Hidetoshi Mino, May 31 2024

A271103 Number of magic and semi-magic squares of order n composed of the numbers from 1 to n^2, counted up to rotations and reflections.

Original entry on oeis.org

1, 0, 9, 68688, 579043051200, 94590660245399996601600
Offset: 1

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Author

William Walkington, Mar 30 2016

Keywords

Comments

A semi-magic square differs from a magic square in that at least one of its main diagonals does not sum to the magic constant. [Walter Trump]
The number of order 4 magic and semi-magic squares was computed by Mutsumi Suzuki, and could be found on his former web site. Mutsumi Suzuki's pages are now in the Internet Archive.
The number of order 5 magic and semi-magic squares was computed by Walter Trump in March 2000.
The number of order 6 magic and semi-magic squares was calculated by Artem Ripatti in April 2018, and published in his paper dated July 10, 2018. - William Walkington, Jul 17 2018

Crossrefs

Formula

a(n) = A271104(n)* n^2.

Extensions

a(6) added by William Walkington, Jul 17 2018

A270876 Number of magic tori of order n composed of the numbers from 1 to n^2.

Original entry on oeis.org

1, 0, 1, 255, 251449712
Offset: 1

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Author

William Walkington, Mar 24 2016

Keywords

Comments

Initially based on empirical observations by William Walkington, the results for the orders 1 to 4 have since been computed and confirmed by Walter Trump. The results for the order 5 have been computed by Walter Trump.

Crossrefs

Showing 1-3 of 3 results.