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A199264
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Period 18: repeat (9,8,7,6,5,4,3,2,1,0,1,2,3,4,5,6,7,8).
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3
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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
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OFFSET
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0,1
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COMMENTS
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'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
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LINKS
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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).
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FORMULA
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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
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MATHEMATICA
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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 *)
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PROG
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(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
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CROSSREFS
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Cf. A158289.
Sequence in context: A011116 A106334 A089739 * A022965 A023451 A109910
Adjacent sequences: A199261 A199262 A199263 * A199265 A199266 A199267
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KEYWORD
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easy,nonn
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AUTHOR
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Arkadiusz Wesolowski, Nov 04 2011
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STATUS
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approved
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