A199264 Period 18: repeat (9,8,7,6,5,4,3,2,1,0,1,2,3,4,5,6,7,8).

9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5

Offset

0,1

Comments

'Valley and Peak' sequence.

The sequence contains only values less than 10.

abs(a(n)-a(n+1)) = 1.

This sequence is in A158289. - Omar E. Pol, Feb 02 2012

Links

Arkadiusz Wesolowski, Table of n, a(n) for n = 0..10000

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

Formula

a(n) = 9 - A158289(n).

G.f.: ( -9+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8-8*x^9 ) / ( (x-1)*(1+x)*(x^2-x+1)*(x^6-x^3+1) ). - R. J. Mathar, Nov 05 2011

a(n) = A158289(n+9). - Omar E. Pol, Feb 02 2012

a(n) = abs((n mod 18) - 9). - Alonso del Arte, Jul 03 2012

Mathematica

Flatten[Table[{9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8}, {5}]] (* Arkadiusz Wesolowski, Dec 03 2011 *)
(* For Mathematica 7.0+ *) ArrayPad[Range[0, 9], {9, 68}, "Reflected"] (* Arkadiusz Wesolowski, Feb 02 2011 *)
Table[Abs[Mod[n, 18] - 9], {n, 0, 81}] (* Alonso del Arte, Jul 03 2012 *)
PadRight[{}, 90, Join[Range[9, 0, -1], Range[8]]] (* Harvey P. Dale, Apr 08 2013 *)

Prog

(PARI) a(n)=[9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8][n%18+1] \\ Charles R Greathouse IV, Jul 17 2016

Crossrefs

Cf. A158289.

Sequence in context: A011116 A106334 A089739 * A022965 A023451 A109910

Adjacent sequences: A199261 A199262 A199263 * A199265 A199266 A199267

Keyword

easy,nonn

Author

Arkadiusz Wesolowski, Nov 04 2011

Status

approved