A104158 Numbers on a standard, London, or clock dartboard read in a counterclockwise direction.

20, 5, 12, 9, 14, 11, 8, 16, 7, 19, 3, 17, 2, 15, 10, 6, 13, 4, 18, 1, 20, 5, 12, 9, 14, 11, 8, 16, 7, 19, 3, 17, 2, 15, 10, 6, 13, 4, 18, 1, 20, 5, 12, 9, 14, 11, 8, 16, 7, 19, 3, 17, 2, 15, 10, 6, 13, 4, 18, 1, 20, 5, 12, 9, 14, 11, 8, 16, 7, 19, 3, 17, 2, 15, 10, 6

Offset: 0

Author

Andrew G. West (WestA(AT)wlu.edu), Mar 09 2005

Keywords

• nonn
• easy

Comments

Sequence is periodic with period 20. - Michel Marcus, Jul 26 2013

References

• GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 82.

Links

• Paolo Xausa, Table of n, a(n) for n = 0..10000
• K. S. Brown, The Dartboard Sequence
• Patrick Chaplin, Why are the numbers on a dartboard in the order they are?
• Sven Silow, Why this particular numbering scheme?
• Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1).

Crossrefs

Cf. A003833, A008575.

Programs

Mathematica

PadRight[{}, 100, {20, 5, 12, 9, 14, 11, 8, 16, 7, 19, 3, 17, 2, 15, 10, 6, 13, 4, 18, 1}] (* Paolo Xausa, Jul 17 2025 *)