A076451 - OEIS

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A076451

Let w(1)=w(2)=w(3)=1, w(n) = (-1)^floor(n/2)*sign(w(n-1)-w(n-2))*w(n-3), then a(n) = 1+w(n).

2, 2, 2, 1, 0, 2, 1, 2, 2, 1, 2, 2, 1, 2, 0, 1, 2, 2, 1, 0, 0, 1, 2, 0, 1, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 0, 1, 2, 2, 1, 0, 2, 1, 2, 2, 1, 2, 2, 1, 2, 0, 1, 2, 2, 1, 0, 0, 1, 2, 0, 1, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 0, 1, 2, 2, 1, 0, 2, 1, 2, 2, 1, 2, 2, 1, 2, 0, 1, 2, 2, 1, 0, 0, 1, 2, 0, 1, 0, 0, 1, 0, 0, 1, 0, 2

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..105.

FORMULA

A 36-periodic sequence with period (1, 0, 2, 1, 2, 2, 1, 2, 2, 1, 2, 0, 1, 2, 2, 1, 0, 0, 1, 2, 0, 1, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 0, 1, 2, )

From Chai Wah Wu, Jun 12 2020: (Start)

a(n) = a(n-1) - a(n-18) + a(n-19) for n > 20.

G.f.: x*(x^19 - x^18 - x^16 - x^15 + 2*x^14 - x^13 + x^12 - x^10 + x^9 - x^7 + x^6 - 2*x^5 + x^4 + x^3 - 2)/(x^19 - x^18 + x - 1). (End)

CROSSREFS

Sequence in context: A357563 A112215 A176389 * A230536 A306257 A357316

Adjacent sequences: A076448 A076449 A076450 * A076452 A076453 A076454

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Nov 24 2002

STATUS

approved