A363765 Lexicographically earliest sequence of numbers in a hexagonal spiral such that their neighbors have no common digit.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 44, 11, 20, 13, 22, 14, 23, 15, 24, 16, 25, 17, 26, 33, 27, 30, 28, 34, 55, 29, 40, 35, 60, 57, 46, 37, 18, 39, 47, 19, 36, 45, 70, 12, 48, 51, 49, 31, 50, 21, 38, 41, 53, 61, 42, 58, 32, 80, 52, 64, 59, 62, 81, 56, 43, 72

Offset: 1

Author

Carole Dubois, Jun 20 2023

Keywords

• base
• nonn
• fini
• full

Comments

This sequence ends with 672 terms.

Examples

			a(26) = 27 because the neighbors of the 26th hexagon are 10, 30, 33, 44, 48, 51 which have no common digit with 27.
a(673) can't be calculated because its neighbors would be 216, 397, and 548, and they use all digits.
		

Links

• Carole Dubois, Table of n, a(n) for n = 1..672
• Carole Dubois, Hexagonal spiral for A363765

Crossrefs

Cf. A000384, A003458, A014105, A056105.