A184408 - OEIS

%I #24 Jul 20 2019 14:22:51

%S 0,0,0,0,0,0,0,2,6,6,6,6,6,8,12,18,30,30,30,30,30,30,30,34,46,56,60,

%T 60,60,66,80,98,126,126,126,126,126,126,126,130,142,150,150,150,150,

%U 154,166,186,222,248,252,252,252,252,252,260,288,322,344,348,348,364,404,450,510,510,510,510,510,510,510,514,526

%N Number of holes in the toothpick structure of A182840.

%C Each connected group of unoccupied lines in the hexagonal structure enclosed by toothpicks counts as a hole.

%H Olaf Voß, <a href="/A184408/b184408.txt">Table of n, a(n) for n = 0..625</a>

%H N. J. A. Sloane, <a href="/wiki/Catalog_of_Toothpick_and_CA_Sequences_in_OEIS">Catalog of Toothpick and Cellular Automata Sequences in the OEIS</a>

%H Olaf Voß, <a href="/wiki/Toothpick_structures_on_hexagonal_net">Toothpick structures on hexagonal net</a>

%H <a href="/index/To#toothpick">Index entries for sequences related to toothpick sequences</a>

%e Structure after step 8:

%e       \_/

%e     \_/ \_/

%e   \_/ \_/ \_/

%e \_/  _/ \_  \_/

%e / \_/ \_/ \_/ \

%e \_/ \_/ \_/ \_/

%e / \ / \_/ \ / \

%e \_/ \_/ \_/ \_/

%e / \_/ \_/ \_/ \

%e \_/ \_/ \_/ \_/

%e / \_  \_/  _/ \

%e   / \_/ \_/ \

%e     / \_/ \

%e       / \

%e There are 6 holes in this structure, so a(8)=6.

%Y For total number of missing toothpicks see A184409.

%K nonn

%O 0,8

%A _Olaf Voß_, Jan 13 2011