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%I #20 Oct 26 2023 08:32:46
%S 11,9,10,14,12,13,17,15,16,20,18,19,23,21,22,26,24,25,2,0,1,5,3,4,8,6,
%T 7,38,36,37,41,39,40,44,42,43,47,45,46,50,48,49,53,51,52,29,27,28,32,
%U 30,31,35,33,34,65,63,64,68,66,67,71,69,70,74,72,73,77,75
%N Tersum n + 11.
%H <a href="/index/Rec#order_22">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,-1,0,0,0,0,-1,1,0,1,-1,0,0,0,0,-1,1,0,1,-1).
%F Tersum m + n: write m and n in base 3 and add mod 3 with no carries; e.g., 5 + 8 = "21" + "22" = "10" = 1.
%F a(n) = A004489(n, 11). - _Michel Marcus_, Nov 09 2021
%F G.f.: (20*x^21+x^20-2*x^19-16*x^18-7*x^12+x^11-2*x^10+11*x^9-7*x^3+x^2-2*x+11) / ((x^2+x+1)*(x^18+x^9+1)*(x-1)^2). - _Alois P. Heinz_, Nov 09 2021
%o (Python)
%o def a(n):
%o k, pow3, m = 0, 1, 11
%o while n + m > 0:
%o n, rn = divmod(n, 3)
%o m, rm = divmod(m, 3)
%o k, pow3 = k + pow3*((rn+rm)%3), pow3*3
%o return k
%o print([a(n) for n in range(58)]) # _Michael S. Branicky_, Nov 09 2021
%Y Cf. A004489.
%K nonn,base,easy
%O 0,1
%A _N. J. A. Sloane_
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