A236398 Period 4: repeat 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, 2, 1, 1, 1

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: A088951 A361633 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