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