%I A161830
%S A161830 0,1,3,5,9,11,15,19,27,31,35,39,47,53,61,71,89,99,103
%N A161830 Y-toothpick triangle (see Comments lines for definition).
%C A161830 Y-toothpick sequence starting at the corner of an infinite hexagon in 
               which its vertex touch an endpoint of the initial Y-toothpick and 
               the two other endpoints are equidistant from the nearest sides of 
               the hexagon.
%C A161830 The sequence gives the number of Y-toothpicks in the sieve after n rounds. 
               A161831 (the first differences) gives the number added at the nth 
               round.
%C A161830 See the Y-toothpick sequence A160120 for more information about the recursive, 
               fractal-like structure.
%Y A161830 Cf. A139250, A160120, A160121, A160406, A160407, A161831, A161832, A161833.
%Y A161830 Sequence in context: A075991 A002731 A006046 this_sequence A151922 A104635 
               A024903
%Y A161830 Adjacent sequences: A161827 A161828 A161829 this_sequence A161831 A161832 
               A161833
%K A161830 more,nonn
%O A161830 0,3
%A A161830 Omar E. Pol (info(AT)polprimos.com), Jun 20 2009