

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

Table of n, a(n) for n=1..70.
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*(n1))  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(n4) 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



