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 A275606 Spiral constructed on the nodes of the triangular net such that a(n) = signum(A274920(n)). 7
 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0 COMMENTS The structure of the spiral has the following properties: 1) The 1's represent the nodes of the hexagonal net. 2) Every 0 is surrounded by six equidistant 1's. 3) Every 1 is surrounded by three equidistant 0's and three equidistant 1's. 4) Diagonals are periodic sequences with period 3 (A011655). Also the 1's represent the atoms of carbon in graphene. LINKS Wikipedia, Graphene FORMULA a(n) = A057427(A274920(n)). EXAMPLE Illustration of initial terms as a spiral: . .                1 - 0 - 1 - 1 - 0 - 1 .               /                     \ .              0   1 - 1 - 0 - 1 - 1   0 .             /   /                 \   \ .            1   1   0 - 1 - 1 - 0   1   1 .           /   /   /             \   \   \ .          1   0   1   1 - 0 - 1   1   0   1 .         /   /   /   /         \   \   \   \ .        0   1   1   0   1 - 1   0   1   1   0 .       /   /   /   /   /     \   \   \   \   \ .      1   1   0   1   1   0 - 1   1   0   1   1 .       \   \   \   \   \         /   /   /   / .        0   1   1   0   1 - 1 - 0   1   1   0 .         \   \   \   \             /   /   / .          1   0   1   1 - 0 - 1 - 1   0   1 .           \   \   \                 /   / .            1   1   0 - 1 - 1 - 0 - 1   1 .             \   \                     / .              0   1 - 1 - 0 - 1 - 1 - 0 .               \ .                1 - 0 - 1 - 1 - 0 - 1 . CROSSREFS Cf. A011655, A057427, A274820, A274821, A274920, A274921, A275610. Sequence in context: A182067 A196147 A242647 * A211487 A252372 A204447 Adjacent sequences:  A275603 A275604 A275605 * A275607 A275608 A275609 KEYWORD nonn AUTHOR Omar E. Pol, Nov 09 2016 STATUS approved

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