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A176895 Period 4: repeat [1, 4, 2, 4]. 10
1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1, 4, 2, 4, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

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) = 4/gcd(n,4). - Michael Somos, Jan 06 2011

a(n) = (1/24)*{29*(n mod 4)-[(n+1) mod 4]+23*[(n+2) mod 4]-7*[(n+3) mod 4]}. - Paolo P. Lava, Apr 30 2010

a(n) = (11-I^n-5*(-1)^n-(-I)^n)/4 = 11/4-5*(-1)^n/4 -A056594(n)/2, with I=sqrt(-1). - Paolo P. Lava, Apr 30 2010

a(n) = 4-(1+(-1)^n)*(5+I^n)/4. - Bruno Berselli, Mar 22 2011

G.f.: ( 1+4*x+2*x^2+4*x^3 ) / ( (1-x)*(1+x)*(x^2+1) ). - R. J. Mathar, Mar 21 2011

From Wesley Ivan Hurt, Jul 11 2016: (Start)

a(n) = a(n-4) for n>3.

a(n) = 2^((5-(-I)^n-I^n-3*I^(2*n))/4) where I=sqrt(-1). (End)

MAPLE

seq(op([1, 4, 2, 4]), n=0..50); # Wesley Ivan Hurt, Jul 11 2016

MATHEMATICA

PadRight[{}, 100, {1, 4, 2, 4}] (* Wesley Ivan Hurt, Jul 11 2016 *)

PROG

(PARI) a(n)=4/gcd(n, 4) \\ Charles R Greathouse IV, Oct 07 2015

(MAGMA) &cat [[1, 4, 2, 4]^^30]; // Wesley Ivan Hurt, Jul 11 2016

CROSSREFS

Cf. A056594.

Sequence in context: A090976 A156199 A135513 * A335261 A256789 A226577

Adjacent sequences:  A176892 A176893 A176894 * A176896 A176897 A176898

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Apr 28 2010

STATUS

approved

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Last modified April 22 09:30 EDT 2021. Contains 343174 sequences. (Running on oeis4.)