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Strictly decreasing domain set of A005185.
1

%I #10 Dec 05 2022 08:35:20

%S 9,14,17,19,21,24,26,28,30,31,33,35,37,39,40,41,43,44,46,48,50,52,53,

%T 55,57,58,61,62,63,64,65,68,69,71,72,73,75,76,77,78,79,82,83,84,86,87,

%U 88,90,92,93,94,100,104,105,106,107,108,109,110,112,113,114,116,118,119

%N Strictly decreasing domain set of A005185.

%t digits=750;

%t Hofstadter[n_Integer?Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n-1]] + Hofstadter[n - Hofstadter[n-2]];

%t Hofstadter[1] = Hofstadter[2] = 1;

%t a1=Table[Hofstadter[n], {n, 1, digits}];

%t f[x_, y_] := Abs[x-y]/; x-y<0;

%t f[x_, y_] := 0/; x-y>=0;

%t b=Table[If[f[a1[[n]], a1[[n-1]]]>0, a1[[n]], 0], {n, 2, digits}];

%t c=Delete[Union[b], 1]

%Y Cf. A005185.

%K nonn

%O 1,1

%A _Roger L. Bagula_, Sep 29 2003