A010699 Period 2: repeat (2,9).

2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2, 9, 2

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Comments

Continued fraction of 1 + sqrt(11)/3 = A176056. - R. J. Mathar, Nov 21 2011

Links

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

Crossrefs

Equals 2 + A010678 = 2 + 7*A000035.

Programs

Mathematica

PadRight[{},100,{2,9}] (* Harvey P. Dale, Mar 25 2015 *)

PARI

a(n)=n%2*7+2 \\ Charles R Greathouse IV, Jul 13 2016

Formula

a(n) = -7/2*(-1)^n+11/2. - Paolo P. Lava, Oct 20 2006

G.f.: (2+9x)/((1-x)(1+x)). - R. J. Mathar, Nov 21 2011

a(n) = 2 + 7*(n mod 2) = 2 + 7*A000035(n). - M. F. Hasler, Feb 26 2020