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A152822 Periodic sequence [1,1,0,1] of length 4 2
1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..104.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,1).

FORMULA

a(n) = 0.75-.25*(-1)^n+0.5*cos(n*Pi/2) ;

a(n+4) = a(n) with a(0) = a(1) = a(3) = 1 and a(2) = 0 ;

o.g.f f(z) = (1+z+z^3/(1-z^4))

a(n) = (1/8)*{(n mod 4)-[(n+1) mod 4]+3*[(n+2) mod 4][(n+3) mod 4]}, with n >= 0. a(n) = (1/4)*[3+I^n+(-I)^n-(-1)^n], with n >= 0 and I = sqrt(-1) [Paolo P. Lava, Dec 15 2008]

a(n) = ceil(cos(Pi*n/4)^2). - Wesley Ivan Hurt, Jun 12 2013

PROG

(PARI) a(n)=n%4!=2 [From Jaume Oliver Lafont, Mar 24 2009]

CROSSREFS

Cf. A026052, A026064

Sequence in context: A004547 A085369 A046980 * A118831 A118828 A105234

Adjacent sequences:  A152819 A152820 A152821 * A152823 A152824 A152825

KEYWORD

easy,nonn

AUTHOR

Richard Choulet, Dec 13 2008

EXTENSIONS

More terms from Philippe Deléham, Dec 21 2008

STATUS

approved

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Last modified December 5 19:19 EST 2016. Contains 278770 sequences.