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A275610 Hexagonal spiral constructed on the nodes of the triangular net in which every 1 of A275606 is replaced with the least positive integer not yet in the sequence. 6
0, 1, 2, 3, 4, 5, 6, 0, 7, 0, 8, 0, 9, 0, 10, 0, 11, 0, 12, 13, 14, 0, 15, 16, 0, 17, 18, 0, 19, 20, 0, 21, 22, 0, 23, 24, 0, 25, 0, 26, 27, 28, 0, 29, 30, 31, 0, 32, 33, 34, 0, 35, 36, 37, 0, 38, 39, 40, 0, 41, 42, 0, 43, 44, 0, 45, 0, 46, 47, 0, 48, 0, 49, 50, 0, 51, 0, 52, 53, 0, 54, 0, 55, 56, 0, 57, 0, 58, 59, 0, 60 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A way for the enumeration of the nodes of the hexagonal net.

Also a way for the enumeration of the atoms of carbon in graphene.

Also sequence in which every positive integer of A274920 is replaced with the least positive integer not yet in the sequence.

LINKS

Table of n, a(n) for n=0..90.

Wikipedia, Graphene

EXAMPLE

Illustration of initial terms as a spiral:

.

.           9 - 0 - 8

.          /         \

.         0   3 - 2   0

.        /   /     \   \

.      10   4   0 - 1   7

.        \   \         /

.         0   5 - 6 - 0

.          \

.          11 - 0 - 12

.

CROSSREFS

Cf. A274820, A274821, A274920, A274921, A275606.

Sequence in context: A194757 A070553 A204453 * A195830 A080743 A265519

Adjacent sequences:  A275607 A275608 A275609 * A275611 A275612 A275613

KEYWORD

nonn

AUTHOR

Omar E. Pol, Aug 03 2016

STATUS

approved

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Last modified June 5 03:11 EDT 2020. Contains 334828 sequences. (Running on oeis4.)