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A236398 Period 4: repeat 1,1,2,1. 2
1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

REFERENCES

H. Blaine Lawson, Jr. and M.-L. Michelsohn, Spin Geometry, Princeton, p. 33.

LINKS

Table of n, a(n) for n=1..94.

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

FORMULA

a(n) = a(n-4) for n > 4. G.f.: x*(1 + x + 2*x^2 + x^3)/(1 - x^4). - Chai Wah Wu, Jun 04 2016

E.g.f.: (-2 - sin(x) + 3*sinh(x) + 2*cosh(x))/2. - Ilya Gutkovskiy, Jun 04 2016

a(n) = (5-cos(n*Pi)-2*sin(n*Pi/2))/4. - Luce ETIENNE, Feb 17 2017

PROG

(MAGMA) &cat [[1, 1, 2, 1]^^24]; // Bruno Berselli, Dec 10 2015

(PARI) a(n)=n=n%8; if(n==3||n==7, 2, 1) \\ Charles R Greathouse IV, Jul 17 2016

CROSSREFS

Cf. A177704.

Sequence in context: A081418 A088951 A186006 * A107453 A164115 A164117

Adjacent sequences:  A236395 A236396 A236397 * A236399 A236400 A236401

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Jan 29 2014

EXTENSIONS

Definition corrected by Paul Curtz. - N. J. A. Sloane, Oct 10 2016

STATUS

approved

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Last modified February 16 04:47 EST 2019. Contains 320140 sequences. (Running on oeis4.)