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A338201
a(n) is the number of unit perimeter triangles with rational side lengths whose largest denominator is equal to n.
2
0, 0, 1, 0, 1, 0, 2, 1, 2, 1, 4, 2, 5, 2, 5, 4, 8, 4, 10, 8, 10, 6, 14, 8, 15, 9, 16, 14, 21, 13, 24, 16, 23, 16, 41, 18, 33, 20, 33, 32, 40, 32, 44, 34, 53, 30, 52, 32, 54, 35, 54, 48, 65, 38, 87, 70, 67, 49, 80, 64, 85, 56, 116, 64, 116, 73, 102, 80, 96, 99
OFFSET
1,7
COMMENTS
Records occur at n=1, 3, 7, 11, 13, 17, 19, 23, 25, 27, 29, 31, 35, 43, 45, 49, 53, 55, 63, 73, 75, 77, 91, 99, 105, 117, 133, 143, 175, 187, ...
LINKS
Code Golf Stack Exchange, Triangles with rational side lengths
Peter Kagey, Haskell program.
EXAMPLE
For n = 20, the a(20) = 8 triangles have sides:
1/4, 7/20, 2/5;
1/12, 9/20, 7/15;
3/10, 7/20, 7/20;
3/20, 2/5, 9/20;
1/4, 3/10, 9/20;
2/15, 5/12, 9/20;
1/5, 7/20, 9/20; and
1/10, 9/20, 9/20.
CROSSREFS
Sequence in context: A187718 A029196 A051493 * A029173 A002331 A060805
KEYWORD
nonn
AUTHOR
Peter Kagey, Oct 16 2020
STATUS
approved