A010697 Period 2: repeat (2,7).

2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2

Offset

0,1

Comments

Continued fraction expansion of A176054. - R. J. Mathar, Mar 08 2012

Decimal expansion of 3/11. - Franklin T. Adams-Watters, Nov 21 2018

Links

Table of n, a(n) for n=0..80.

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

Formula

G.f.: (2+7x)/((1-x)(1+x)). - R. J. Mathar, Nov 21 2011

a(n) = A010888(2^n+5^n) = A010888(A074600(n)). - Peter M. Chema, Jul 13 2016

E.g.f.: 7*sinh(x) + 2*cosh(x). - Ilya Gutkovskiy, Jul 14 2016

a(n) = 14/a(n-1). - Nicolas Bělohoubek, Nov 11 2021

Mathematica

Table[-5/2*(-1)^n + 9/2, {n, 0, 120}] (* or *)
Table[7 Mod[n, 2] + 2 Mod[(n + 1), 2], {n, 0, 120}] (* or *)
CoefficientList[Series[(2 + 7 x)/((1 - x) (1 + x)), {x, 0, 120}], x] (* or *)
Table[NestWhile[Total@ IntegerDigits@ # &, 2^n + 5^n, IntegerLength@ # > 1 &], {n, 0, 120}] (* Michael De Vlieger, Jul 13 2016 *)

Prog

(PARI) a(n)=if(n%2, 7, 2) \\ Charles R Greathouse IV, Oct 07 2015

Crossrefs

Cf. A010888, A074600.

Sequence in context: A151869 A262083 A181284 * A088666 A170854 A215140

Adjacent sequences: A010694 A010695 A010696 * A010698 A010699 A010700

Keyword

nonn,easy

Author

N. J. A. Sloane.

Status

approved