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A137797 a(n) = 2*( (n+1) mod 5 ) - 2*( (n+1) mod 2 ). 1
0, 4, 4, 8, -2, 2, 2, 6, 6, 0, 0, 4, 4, 8, -2, 2, 2, 6, 6, 0, 0, 4, 4, 8, -2, 2, 2, 6, 6, 0, 0, 4, 4, 8, -2, 2, 2, 6, 6, 0, 0, 4, 4, 8, -2, 2, 2, 6, 6, 0, 0, 4, 4, 8, -2, 2, 2, 6, 6, 0, 0, 4, 4, 8, -2, 2, 2, 6, 6, 0, 0, 4, 4, 8, -2, 2, 2, 6, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The sequence is periodic with period 10. - Colin Barker, Dec 16 2014

LINKS

Table of n, a(n) for n=0..78.

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

FORMULA

a(n) = -a(n-1)+a(n-5)+a(n-6) for n>5. - Colin Barker, Dec 16 2014

G.f.: -2*x*(3*x^3+6*x^2+4*x+2) / ((x-1)*(x+1)*(x^4+x^3+x^2+x+1)). - Colin Barker, Dec 16 2014

EXAMPLE

a(2) = 2*((2+1) mod 5) - 2*((2+1) mod 2) = 2*(3 mod 5) - 2*(3 mod 2) = 4.

MATHEMATICA

LinearRecurrence[{-1, 0, 0, 0, 1, 1}, {0, 4, 4, 8, -2, 2}, 100] (* Harvey P. Dale, Jun 08 2015 *)

PROG

(PARI) concat(0, Vec(-2*x*(3*x^3+6*x^2+4*x+2)/((x-1)*(x+1)*(x^4+x^3+x^2+x+1)) + O(x^100))) \\ Colin Barker, Dec 16 2014

CROSSREFS

Suggested by A010700. Used in A137798.

Sequence in context: A067736 A181387 A091671 * A176295 A140874 A021227

Adjacent sequences:  A137794 A137795 A137796 * A137798 A137799 A137800

KEYWORD

easy,sign

AUTHOR

William A. Tedeschi, Feb 10 2008

STATUS

approved

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Last modified September 17 16:32 EDT 2021. Contains 347487 sequences. (Running on oeis4.)