A133292 Period 9: repeat [1, 1, 2, 4, 7, 2, 7, 4, 2].

1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2, 7, 4, 2, 1, 1, 2, 4, 7, 2

Offset: 0

Author

Paul Curtz, Oct 17 2007

Keywords

• nonn
• easy
• less

Comments

For n>0, digital roots of centered 10-gonal numbers (A062786). - Colin Barker, Jan 30 2015

For n>0, also the digital roots of central polygonal numbers (the Lazy Caterer's sequence) A000124. - Peter M. Chema, Sep 17 2016

Links

• Colin Barker, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,0,1).

Crossrefs

Cf. A000124, A062786.

Programs

Mathematica

PadRight[{},111,{1,1,2,4,7,2,7,4,2}] (* Harvey P. Dale, Apr 29 2012 *)

PARI

a(n)=[1,1,2,4,7,2,7,4,2][n%9+1] \\ Charles R Greathouse IV, Jun 02 2011

PARI

Vec(-(2*x^8+4*x^7+7*x^6+2*x^5+7*x^4+4*x^3+2*x^2+x+1)/((x-1)*(x^2+x+1)*(x^6+x^3+1)) + O(x^100)) \\ Colin Barker, Apr 04 2015

Formula

G.f.: -(2*x^8+4*x^7+7*x^6+2*x^5+7*x^4+4*x^3+2*x^2+x+1) / ((x-1)*(x^2+x+1)*(x^6+x^3+1)). - Colin Barker, Apr 04 2015

a(n) = a(n-9). - Wesley Ivan Hurt, May 09 2022