A010695 Period 2: repeat (2,5).

2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5, 2, 5

Offset

0,1

Comments

Also decimal expansion of 25/99.

Continued fraction expansion of A176052. - R. J. Mathar, Mar 08 2012

Periodic part of the partial quotients of the continued fraction expansion of sqrt(7/5), which starts [1, 5, 2, 5, 2, 5, ...]. - Hugo Pfoertner, Jan 10 2025

Links

Table of n, a(n) for n=0..87.

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

Formula

G.f.: (2+5*x)/((1-x)*(1+x)). - R. J. Mathar, Nov 21 2011

a(n) = 2^(1-(-1)^n) + 1. - Bruno Berselli, Dec 29 2015

From Nicolas Bělohoubek, Nov 11 2021: (Start)

a(n) = 10/a(n-1). See also A010691.

a(n) = 7 - a(n-1). See also A010702. (End)

Mathematica

PadRight[{}, 100, {2, 5}] (* Paolo Xausa, Jan 16 2025 *)

Prog

(Maxima) makelist(if evenp(n) then 2 else 5, n, 0, 80); /* Martin Ettl, Nov 09 2012 */
(Magma) &cat [[2, 5]^^50]; // Bruno Berselli, Dec 29 2015

Crossrefs

Cf. A010674 (2^(1-(-1)^n) - 1).

Cf. A010691.

Sequence in context: A220342 A221676 A073054 * A021400 A059855 A082881

Adjacent sequences: A010692 A010693 A010694 * A010696 A010697 A010698

Keyword

nonn,easy

Author

N. J. A. Sloane

Extensions

Edited by Bruno Berselli, Dec 29 2015

Status

approved