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.

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

Offset: 0

Author

Omar E. Pol, Aug 03 2016

Keywords

• nonn

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.

Examples

			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
.
		

Links

• Wikipedia, Graphene

Crossrefs

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