A094225 Number of distinct n-row absolute difference tables that consist entirely of the first A000217(n) natural numbers.
1, 2, 4, 4, 1
Offset: 1
Examples
Illustrating the case of the unique example of n=5 with numbers 1 through 15: 6..14.15..3..13 ..8..1..12.10 ...7..11..2 ....4...9 ......5 For n=2 we have 1,3;2 and 2,3;1 so a(2) = 2. - _Michael Somos_, Apr 07 2012
References
- M. Gardner, "Pool-Ball Triangles", pp. 119-120 and 128, Penrose Tiles to Trapdoor Ciphers, Freeman NY 1989.
- M. Gardner, Puzzles From Other Worlds, Problem 8, pp. 143; 173, Random House NY 1984.
- J. D. E. Konhauser et al., " Difference triangles", Problem 145, pp. 43; 184-6, Which Way Did The Bicycle Go, MAA 1996.
- P. Tougne, " Jeux Mathematiques", Aug. 1982 issue of Pour La Science (French edition of 'Scientific American'), Paris.
Links
- D. Greenwell, Pool-ball Triangles.
- T. Sillke, Absolute-difference triangles
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