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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A360920 Array read by antidiagonals: T(m,n) is the maximum number of vertices in an induced tree in the grid graph P_m X P_n.

Original entry on oeis.org

1, 2, 2, 3, 3, 3, 4, 5, 5, 4, 5, 6, 7, 6, 5, 6, 8, 9, 9, 8, 6, 7, 9, 12, 12, 12, 9, 7, 8, 11, 14, 15, 15, 14, 11, 8, 9, 12, 16, 18, 19, 18, 16, 12, 9, 10, 14, 18, 21, 22, 22, 21, 18, 14, 10, 11, 15, 21, 24, 26, 26, 26, 24, 21, 15, 11, 12, 17, 23, 27, 30, 31, 31, 30, 27, 23, 17, 12
Offset: 1

Views

Author

Andrew Howroyd, Feb 26 2023

Keywords

Examples

			Array begins:
===============================================
  m\n|  1  2  3  4  5  6  7  8  9 10 11  12 ...
-----+-----------------------------------------
   1 |  1  2  3  4  5  6  7  8  9 10 11  12 ...
   2 |  2  3  5  6  8  9 11 12 14 15 17  18 ...
   3 |  3  5  7  9 12 14 16 18 21 23 25  27 ...
   4 |  4  6  9 12 15 18 21 24 27 30 33  36 ...
   5 |  5  8 12 15 19 22 26 30 34 37 41  44 ...
   6 |  6  9 14 18 22 26 31 35 39 44 48  52 ...
   7 |  7 11 16 21 26 31 36 41 46 51 56  61 ...
   8 |  8 12 18 24 30 35 41 46 52 58 63  69 ...
   9 |  9 14 21 27 34 39 46 52 59 65 71  78 ...
  10 | 10 15 23 30 37 44 51 58 65 72 79  86 ...
  11 | 11 17 25 33 41 48 56 63 71 79 87  94 ...
  12 | 12 18 27 36 44 52 61 69 78 86 94 102 ...
  ...
		

Crossrefs

Main diagonal is A360921.
Cf. A360915, A360917, A360918 (maximum induced trees).

Formula

T(m,n) = T(n,m).

A360919 Number of maximum induced trees in the n X n grid graph.

Original entry on oeis.org

1, 4, 10, 32, 22, 4120, 488, 65864, 166, 1296, 872, 37652512, 678412, 1858036816, 337856
Offset: 1

Views

Author

Andrew Howroyd, Feb 26 2023

Keywords

Comments

A maximum induced tree is an induced tree of greatest size.

Examples

			The a(3) = 10 maximum induced trees are the following subgraphs and their rotations and reflections.
   O O O    O O O    O O O
   O        O   O      O
   O O O      O O    O O O
.
The a(4) = 32 maximum induced trees are the following subgraphs and their rotations and reflections.
    O O O O    O O O      O O O O    O O   O
    O     O    O   O O      O   O      O O O
    O O   O    O O   O    O O   O    O O   O
    O   O O    O   O O    O   O O    O   O O
		

Crossrefs

Main diagonal of A360918.
Cf. A360203 (induced trees), A360921 (maximum sizes).
Showing 1-2 of 2 results.