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A152889
Periodic sequence [1,0,4,0,0] of period 5.
1
1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0, 1, 0, 4, 0, 0
OFFSET
0,3
FORMULA
a(n+5) = a(n) with a(0) = 1, a(2) = a(3) = a(4) = 0 and a(2) = 4.
O.g.f: (1+4z^2)/(1-z^5).
a(n) = 1-2/5*5^(1/2)*cos(2*n*Pi/5)+2/5*2^(1/2)*(5-5^(1/2))^(1/2)*sin(2*n*Pi/5) + 2/5*5^(1/2)*cos(4*n*Pi/5)-2/5*2^(1/2)*(5+5^(1/2))^(1/2)*sin(4*n*Pi/5).
CROSSREFS
Cf. A026048.
Sequence in context: A096623 A171914 A200627 * A216273 A327517 A376504
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, Dec 14 2008
EXTENSIONS
More terms from Philippe Deléham, Dec 29 2008
STATUS
approved