A100796 - OEIS

%I #9 Mar 30 2012 18:40:21

%S 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,

%T 16,11,18,16,10,11,11,11,14,11,16,11,18,16,40,14,14,14,11,14,46,14,48,

%U 46,10,11,11,11,14,11,16,11,18,16,60,16,16,16,46,16,66,16,68,66,10,11,11

%N Equivalence class of numerical representation of n. See Comments for definition.

%C 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.

%C 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}.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/FigureEight.html">Figure Eight</a>.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Circle.html">Circle</a>.

%K nonn,less

%O 0,5

%A _Jonathan Vos Post_, Jun 06 2007

%E Edited by _N. J. A. Sloane_, Oct 07 2007

%E More terms from _David Wasserman_, Mar 04 2008