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A100796
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Equivalence class of numerical representation of n. See Comments for definition.
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0
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0, 1, 1, 1, 4, 1, 6, 1, 8, 6, 10, 11, 11, 11, 14, 11, 16, 11, 18, 16, 10, 11, 11, 11, 14, 11, 16, 11, 18, 16, 10, 11, 11, 11, 14, 11, 16, 11, 18, 16, 40, 14, 14, 14, 11, 14, 46, 14, 48, 46, 10, 11, 11, 11, 14, 11, 16, 11, 18, 16, 60, 16, 16, 16, 46, 16, 66, 16, 68, 66, 10, 11, 11
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OFFSET
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0,5
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COMMENTS
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The 10 digits 0,1,...,9 (written in a sans serif font) are covered by 5 equivalence classes: C_0 = {0}, a circle; C_1 = {1, 2, 3, 5, 7}, a line segment; C_4 = {4}, a circle with a point to which is glued two line segments; C_6 = {6, 9}, a circle with a point to which is glued a line segment; C_8 = {8}, a figure eight.
This is different from the topological classification, which would classify the digits according to their genus: {1,2,3,5,7}, {0,4,6,9} and {8}.
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LINKS
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Eric Weisstein's World of Mathematics, Circle.
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CROSSREFS
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KEYWORD
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nonn,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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