A321542 a(0)=1; thereafter a(n) = 3*a(n-1) with digits rearranged into nondecreasing order.
1, 3, 9, 27, 18, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135, 45, 135
Offset: 0
Links
- Paolo Xausa, Table of n, a(n) for n = 0..10000
- Index entries for linear recurrences with constant coefficients, signature (0,1).
Crossrefs
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).
Programs
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Mathematica
A321542list[nmax_]:=PadRight[{1,3,9,27,18},nmax+1,{135,45}];A321542list[100] (* Paolo Xausa, Aug 10 2023 *)
Formula
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
Comments