Loeschian number

Loeschian number
Named after August Lösch
Subsequence of A032766
Formula x2 + xy + y2 for integer x, y
First terms 0, 1, 3, 4, 7, 9, 12, 13, 16
OEIS index

Loeschian numbers take the quadratic form x2 + xy + y2 for integer x, y. They correspond to the norms of vectors in an A2 lattice.

References

  • Marshall, J. U. (1975). "The Loeschian numbers as a problem in number theory". Geographical Analysis. 7: 421–426.
  • "A003136". On-Line Encyclopedia of Integer Sequences. Retrieved 19 July 2018.


This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.