A105397 Periodic with period 2: repeat [4,2].

4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2

Offset

0,1

Comments

A simple "Fractal Jump Sequence" (FJS). An FJS is a sequence of digits containing an infinite number of copies of itself. Modus operandi: underline the first digit "a" of such a sequence then jump over the next "a" digits and underline the digit "b" on which you land. Jump from there over the next "b" digits and underline the digit "c" on which you land. Etc. The "abc...n..." succession of underlined digits is the sequence itself.

Simple continued fraction of 2+sqrt(6). - R. J. Mathar, Nov 21 2011

Links

Table of n, a(n) for n=0..101.

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

Formula

a(n) = 3 + (-1)^n = 4 - 2*(n mod 2) = 2 * 2^((n+1) mod 2). - Wesley Ivan Hurt, Mar 14 2014

Maple

A105397:=n->3 + (-1)^n; seq(A105397(n), n=0..100); # Wesley Ivan Hurt, Mar 14 2014

Mathematica

Table[3 + (-1)^n, {n, 0, 100}] (* Wesley Ivan Hurt, Mar 14 2014 *)
LinearRecurrence[{0, 1}, {4, 2}, 75] (* Ray Chandler, Aug 25 2015 *)

Prog

(PARI) contfrac(2+sqrt(6)) \\ Michel Marcus, Mar 18 2014

Crossrefs

Cf. A010694 (period 2, repeat [2,4]).

First differences of A007310. - Fred Daniel Kline, Aug 17 2020

Sequence in context: A064127 A178253 A209272 * A328999 A236185 A300004

Adjacent sequences: A105394 A105395 A105396 * A105398 A105399 A105400

Keyword

easy,nonn

Author

Eric Angelini, May 01 2005

Extensions

Edited by N. J. A. Sloane, Jun 08 2010

Status

approved