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A154811 a(n) = Fibonacci(2*n+1) mod 9. 9

%I #33 Feb 21 2024 01:47:50

%S 1,2,5,4,7,8,8,7,4,5,2,1,1,2,5,4,7,8,8,7,4,5,2,1,1,2,5,4,7,8,8,7,4,5,

%T 2,1,1,2,5,4,7,8,8,7,4,5,2,1,1,2,5,4,7,8,8,7,4,5,2,1,1,2,5,4,7,8,8,7,

%U 4,5,2,1

%N a(n) = Fibonacci(2*n+1) mod 9.

%C Periodic with period length 12.

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,-1,1).

%F a(n) = A001519(n+1) mod 9 = A122367(n) mod 9 = |A099496(n)| mod 9.

%F From _R. J. Mathar_, Apr 10 2009: (Start)

%F a(n) = a(n-1) - a(n-6) + a(n-7).

%F G.f.: -(1 + x + 3*x^2 - x^3 + 3*x^4 + x^5 + x^6)/((x - 1)*(x^2 + 1)*(x^4 - x^2 + 1)). (End)

%t Mod[Fibonacci[Range[1,151,2]],9] (* _Harvey P. Dale_, Jul 10 2018 *)

%o (PARI) a(n)=fibonacci(n%12*2+1)%9 \\ _Charles R Greathouse IV_, Dec 21 2011

%Y Cf. A010689, A010875.

%K nonn,easy

%O 0,2

%A _Paul Curtz_, Jan 15 2009

%E Edited by _R. J. Mathar_, Jan 23 2009

%E Typo in A-number in first formula corrected by _R. J. Mathar_, Feb 23 2009

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)