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A241231
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Number of triangles, distinct up to congruence, on a centered hexagonal grid of size n.
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5
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0, 4, 34, 134, 379, 866, 1718, 3085, 5149, 8095, 12188, 17664, 24781, 33861, 45269, 59327, 76461, 97017, 121458, 150379, 184053, 223137, 268117, 319578, 378132, 444455, 519178, 602675, 696102, 800051, 914995, 1042094, 1181858, 1335414, 1503251, 1686811, 1886417, 2103007
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OFFSET
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1,2
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COMMENTS
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A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice.
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LINKS
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Eric Weisstein's World of Mathematics, Hex Number.
Eric Weisstein's World of Mathematics, Triangle.
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FORMULA
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EXAMPLE
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For n = 2 the four kinds of non-congruent triangles are the following:
/. * * * . * * .
. * * . . * * . * . . *
\. . . . . . * .
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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