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 1-1 of 1 results.

A329094 a(n) is the number of solutions when placing the numbers 1..n in an n X n square according to the rules in the Comments section.

Original entry on oeis.org

1, 1, 1, 1, 1, 3, 3, 8, 17, 18, 51, 69, 126, 286, 485, 1180, 2245, 4312, 7247, 19559, 41403, 66454, 161131, 337495, 710899, 1286527, 3069554, 7100614, 15046664, 29090692, 57797782, 144576706, 313441617, 628544270, 1278592587, 3304149943, 7192582862
Offset: 1

Views

Author

Lars Blomberg, Nov 04 2019

Keywords

Comments

Place a 1 in the upper left corner of the square. Let k be the number placed last. At each step place k+1 at a distance k vertically or horizontally from k. Solutions are counted up to mirroring in the backward diagonal. That is, all solutions have 2 to the right of 1. Obviously, n is the largest possible value since the next step will inevitably lead outside the square.

Examples

			Sample solutions:
  n=6                  n=7                     n=8
  1  2  -  -  -  -     1  2  -  -  -  -  -     1  2  -  -  -  -  8  -
  -  -  -  -  -  -     7  5  -  -  -  -  6     -  -  -  -  -  -  -  -
  -  3  -  -  -  -     -  3  -  -  -  -  -     5  3  -  -  4  -  -  -
  -  -  -  -  -  -     -  -  -  -  -  -  -     -  -  -  -  -  -  -  -
  -  -  -  -  -  -     -  -  -  -  -  -  -     -  -  -  -  -  -  -  -
  6  4  -  -  -  5     -  4  -  -  -  -  -     -  -  -  -  -  -  -  -
                       -  -  -  -  -  -  -     -  -  -  -  -  -  -  -
                                               6  -  -  -  -  -  7  -

Crossrefs

Cf. A308353.
Showing 1-1 of 1 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.