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%I #21 Aug 19 2016 02:32:54
%S 1,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,
%T 1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,
%U 1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1,7,1,1
%N A simple "Fractal Jump Sequence" (FJS).
%C See A105397 for definition of Fractal Jump Sequence.
%C a(n+2) = the digital root of the n-th centered hexagonal number (A003215). - _Colin Barker_, Jan 30 2015
%H Colin Barker, <a href="/A105395/b105395.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,1).
%F a(n) = a(n-3) for n>4. - _Colin Barker_, Jan 30 2015
%F G.f.: -x*(2*x+1)*(3*x^2-x+1) / ((x-1)*(x^2+x+1)). - _Colin Barker_, Jan 30 2015
%o (PARI) Vec(-x*(2*x+1)*(3*x^2-x+1)/((x-1)*(x^2+x+1)) + O(x^100)) \\ _Colin Barker_, Jan 30 2015
%Y Cf. A003215, A105397, A003215.
%K base,easy,nonn
%O 1,4
%A _Eric Angelini_, May 01 2005
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