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A258186
a(n) is the maximal number of circles that can be enclosed by a closed chain of n circles; all circles' centers lie at coordinate points of the planar net 6.6.6.
1
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 6, 6, 7, 7, 10, 10, 13
OFFSET
0,15
COMMENTS
Inspired by A257594, in which the centers of circles can be considered to be placed on coordinate points of the planar net 3.3.3.3.3.3. See illustrations in the links.
CROSSREFS
Cf. A257594.
Sequence in context: A101081 A373612 A147795 * A357415 A038716 A168659
KEYWORD
nonn,more
AUTHOR
Kival Ngaokrajang, May 23 2015
STATUS
approved