A131707 Period 12: repeat 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9 .

1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7, 3, 3, 9, 1, 1, 3, 7, 7, 1, 9, 9, 7

Offset: 0

Author

Paul Curtz, Sep 14 2007

Keywords

• nonn
• easy

Comments

Also the decimal expansion of 1023949/9000009. [R. J. Mathar, Feb 07 2009]

Links

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

Crossrefs

Cf. A131711.

Programs

Mathematica

PadRight[{},120,{1,1,3,7,7,1,9,9,7,3,3,9}] (* Harvey P. Dale, May 02 2012 *)

Formula

a(n) = A001333(n) mod 10. - Paul Curtz, Apr 08 2008

G.f.: (1+2x^2+4x^3-6x^5+9x^6)/((1-x)(1+x^2)(1-x^2+x^4)). a(n)=a(n-1)-a(n-6)+a(n-7). [R. J. Mathar, Feb 07 2009]

a(n) = 5-2*cos(Pi*n/6) -2*sin(Pi*n/6)/3 -10*sin(Pi*n/2)/3 -2*cos(5*Pi*n/6) -2*sin(5*Pi*n/6)/3. - R. J. Mathar, Oct 08 2011

Extensions

More terms from Tracy Poff (tracy.poff(AT)gmail.com), Dec 21 2008

Even more periods from R. J. Mathar, Feb 07 2009