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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A307170 Minimum number of partial loops in a diagonal Latin square of order n.

Original entry on oeis.org

0, 0, 0, 12, 0, 21, 0, 24
Offset: 1

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Author

Eduard I. Vatutin, Mar 27 2019

Keywords

Comments

A loop in a Latin square is a sequence of cells v1=L[i1,j1] -> v2=L[i1,j2] -> v1=L[i2,j2] -> ... -> v2=L[im,j1] -> v1=L[i1,j1] of length 2*m that consists of a pair of values {v1, v2}. A partial loop is a loop with length < 2*n.
From Eduard I. Vatutin, Oct 20 2020: (Start)
Every intercalate is a partial loop and every partial loop is a loop, so 0 <= A307163(n) <= a(n) <= A307166(n).
0 <= a(n) <= A307171(n).
(End)

Examples

			For example, the square
  2 4 3 5 0 1
  1 0 4 3 2 5
  0 2 5 4 1 3
  5 3 0 1 4 2
  4 5 1 2 3 0
  3 1 2 0 5 4
has a loop
  2 4 . . . .
  . . . . . .
  . 2 . 4 . .
  . . . . . .
  4 . . 2 . .
  . . . . . .
consisting of the sequence of cells L[1,1]=2 -> L[1,2]=4 -> L[3,2]=2 -> L[3,4]=4 -> L[5,4]=2 -> L[5,1]=4 -> L[1,1]=2 with length 6 < 12.
The total number of loops for this square is 21, all of which are partial.
		

Crossrefs

Extensions

a(8) added by Eduard I. Vatutin, Oct 05 2020
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