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A233820 Period 4: repeat [20, 5, 15, 10]. 0
20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5, 15, 10, 20, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Clockwise sectors around outside of London Fives dartboard.
LINKS
Wikipedia, Darts
FORMULA
From Bruno Berselli, Dec 16 2013: (Start)
G.f.: 5*x*(4 + x + 3*x^2 + 2*x^3)/((1 - x)*(1 + x)*(1 + x^2)).
a(n) = 5*(I^(n*(n-1)) - 2*(-1)^n + 5)/2. (End)
From Wesley Ivan Hurt, Jul 07 2016: (Start)
a(n) = 5*(5 + cos(n*Pi/2) - 2*cos(n*Pi) + sin(n*Pi/2) - 2*I*sin(n*Pi))/2.
a(n) = a(n-4) for n>4. (End)
MAPLE
seq(op([20, 5, 15, 10]), n=0..50); # Wesley Ivan Hurt, Jul 07 2016
MATHEMATICA
Flatten[Table[{20, 5, 15, 10}, {17}]]
PROG
(Magma) &cat[[20, 5, 15, 10]: n in [1..17]]; // Bruno Berselli, Dec 16 2013
(PARI) a(n)=[10, 20, 5, 15][n%4+1] \\ Charles R Greathouse IV, Aug 20 2015
CROSSREFS
Cf. A003833.
Sequence in context: A309321 A104158 A068612 * A040387 A201137 A040385
KEYWORD
nonn,easy
AUTHOR
STATUS
approved

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Last modified April 16 04:02 EDT 2024. Contains 371696 sequences. (Running on oeis4.)