A142702 Period 4: repeat [5, 2, 5, 8].

5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8, 5, 2, 5, 8

Offset

1,1

Comments

From Balmer spectrum of hydrogen.

Links

Table of n, a(n) for n=1..84.

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

Formula

a(n) = 5+3*cos(n*Pi/2). [From PARI program of Lafont, Aug 30 2009].

G.f.: ( 5-3*x+8*x^2 ) / ( (1-x)*(1+x^2) ). - R. J. Mathar, Apr 02 2011

a(n) = a(n-1) - a(n-2) + a(n-3) for n>3. - Wesley Ivan Hurt, Jul 08 2016

Maple

seq(op([5, 2, 5, 8]), n=1..50); # Wesley Ivan Hurt, Jul 08 2016

Mathematica

PadRight[{}, 100, {5, 2, 5, 8}] (* Harvey P. Dale, Dec 09 2013 *)

Prog

(PARI) a(n)=5+3*cos(n*Pi/2) \\ [Jaume Oliver Lafont, Aug 30 2009]
(Magma) &cat [[5, 2, 5, 8]^^30]; // Wesley Ivan Hurt, Jul 08 2016

Crossrefs

Sequence in context: A087300 A074455 A339161 * A236184 A201530 A085997

Adjacent sequences: A142699 A142700 A142701 * A142703 A142704 A142705

Keyword

nonn,easy

Author

Paul Curtz, Sep 23 2008

Extensions

Edited by N. J. A. Sloane, Sep 27 2008

Status

approved