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.

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A081287 Excess area when consecutive squares of sizes 1 to n are packed into the smallest possible rectangle.

Original entry on oeis.org

0, 1, 1, 5, 5, 8, 14, 6, 15, 20, 7, 17, 17, 20, 25, 16, 9, 30, 21, 20, 33, 27, 28, 28, 22, 29, 26, 35, 31, 31, 34, 35
Offset: 1

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Author

Ed Pegg Jr, Mar 16 2003

Keywords

Comments

Restricted to packings with the squares aligned with the sides of the rectangle.

Examples

			Verified best rectangles > 5 are as follows:
 6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24  25 26 27  28  29  30  31  32
--------------------------------------------------------------------------------------
 9 11 14 15 15 19 23 22 23 23 28 39 31 47 34 38 39 64 56  43 70 74  63  81  51  95  85
11 14 15 20 27 27 29 38 45 55 54 46 69 53 85 88 98 68 88 129 89 94 123 106 186 110 135
Visual representations are at the Tightly Packed Squares link.
		

References

  • R. K. Guy, Unsolved Problems in Geometry, Section D4, has information about several related problems.
  • R. M. Kurchan (editor), Puzzle Fun, Number 18 (December 1997), pp. 9-10.

Crossrefs

Formula

a(n) = A038666(n) - A000330(n). - Pontus von Brömssen, Mar 01 2024

Extensions

Four extra terms computed by Korf, May 24 2005
More terms from Ed Pegg Jr, Feb 14 2008 and again Sep 16 2009

A365236 a(n) is the least number of integer-sided squares that can be packed together with the n squares 1 X 1, 2 X 2, ..., n X n to fill out a rectangle.

Original entry on oeis.org

0, 1, 1, 3, 2, 4, 3, 3, 4
Offset: 1

Views

Author

Keywords

Comments

Warning: several terms are provisional as their intended verification effectively assumed the augmenting squares were not larger than n X n. - Peter Munn, Oct 02 2023
The definition does not exclude squares larger than n X n.
Terms for n < 10 were verified by the use of a program.
a(10) <= 5.

Examples

			Compositions of rectangles that satisfy the minimal number of augmenting squares for n. Where more than one minimal composition exists for a given n, the table shows a single example. In the table body, the numbers include both the specific mandatory and augmenting squares. a(n) is the total number of squares in the rectangle minus n.
           | 1^2   2^2   3^2   4^2   5^2   6^2   7^2   8^2   9^2  10^2 | Total
  ----------------------------------------------------------------------------
  a(1) = 0 |  1                                                        |   1
  a(2) = 1 |  2     1                                                  |   3
  a(3) = 1 |  2     1     1                                            |   4
  a(4) = 3 |  2     1     2     2                                      |   7
  a(5) = 2 |  2     1     1     2     1                                |   7
  a(6) = 4 |  2     1     3     2     1     1                          |  10
  a(7) = 3 |  1     1     1     3     1     2     1                    |  10
  a(8) = 3 |  3     2     1     1     1     1     1     1              |  11
  a(9) = 4 |  2     2     2     2     1     1     1     1     1        |  13
		

Crossrefs

Formula

a(n) <= 1 + Sum_{k = 1 .. ceiling((n - 1)/2)} (n + (1 - k)*floor(n/k) - 2). This upper bound corresponds to placing the squares with length n up to n - floor((n - 1)/2) all in one row. The remaining mandatory squares will then fit naturally into the rectangle n X (1/2)*(2*n - ceiling((n - 1)/2))*(ceiling((n - 1)/2) + 1).
a(n) > a(n - 1) - 2.

Extensions

Edited by Peter Munn, Oct 04 2023
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