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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 Index entries for linear recurrences with constant coefficients, signature (0,0,0,1). 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 Adjacent sequences:  A233817 A233818 A233819 * A233821 A233822 A233823 KEYWORD nonn,easy AUTHOR Arkadiusz Wesolowski, Dec 16 2013 STATUS approved

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Last modified December 14 03:31 EST 2019. Contains 329978 sequences. (Running on oeis4.)