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%I #21 Aug 10 2023 13:13:49
%S 1,3,9,27,18,45,135,45,135,45,135,45,135,45,135,45,135,45,135,45,135,
%T 45,135,45,135,45,135,45,135,45,135,45,135,45,135,45,135,45,135,45,
%U 135,45,135,45,135,45,135,45,135,45,135,45,135
%N a(0)=1; thereafter a(n) = 3*a(n-1) with digits rearranged into nondecreasing order.
%C For n >= 5, alternates between 45 and 135.
%H Paolo Xausa, <a href="/A321542/b321542.txt">Table of n, a(n) for n = 0..10000</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F G.f.: (-117*x^6 - 18*x^5 - 9*x^4 - 24*x^3 - 8*x^2 - 3*x - 1)/(x^2 - 1). - _Chai Wah Wu_, Nov 20 2018
%t A321542list[nmax_]:=PadRight[{1,3,9,27,18},nmax+1,{135,45}];A321542list[100] (* _Paolo Xausa_, Aug 10 2023 *)
%Y The following are parallel families: A000079 (2^n), A004094 (2^n reversed), A028909 (2^n sorted up), A028910 (2^n sorted down), A036447 (double and reverse), A057615 (double and sort up), A263451 (double and sort down); A000244 (3^n), A004167 (3^n reversed), A321540 (3^n sorted up), A321539 (3^n sorted down), A163632 (triple and reverse), A321542 (triple and sort up), A321541 (triple and sort down).
%K nonn,base
%O 0,2
%A _N. J. A. Sloane_, Nov 19 2018
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