Template:Sequence of the Day for November 20

Intended for: November 20, 2012

Timetable

• First draft entered by Alonso del Arte on November 23, 2011 based on remarks by Jon Wild and Neil Sloane ✓
• Draft to be reviewed by September 20, 2011
• Draft to be approved by October 20, 2011

Yesterday's SOTD * Tomorrow's SOTD

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A200000: Number of meanders filling out an n ×  n grid (reduced for symmetry).

{ 1, 1, 0, 4, 42, 9050, 6965359 ... }

The sequence counts the distinct closed paths that visit every cell of an

n  ×   n

square lattice at least once, that never cross any edge between adjacent squares more than once, and that do not self-intersect. Paths related by rotation and/or reflection of the square lattice are not considered distinct.

This sequence is the official selection to commemorate the milestone of the OEIS containing two hundred thousand sequences, which was reached exactly a year ago today.