A087722 Strictly decreasing domain set of A005185.

9, 14, 17, 19, 21, 24, 26, 28, 30, 31, 33, 35, 37, 39, 40, 41, 43, 44, 46, 48, 50, 52, 53, 55, 57, 58, 61, 62, 63, 64, 65, 68, 69, 71, 72, 73, 75, 76, 77, 78, 79, 82, 83, 84, 86, 87, 88, 90, 92, 93, 94, 100, 104, 105, 106, 107, 108, 109, 110, 112, 113, 114, 116, 118, 119

Offset: 1

Author

Roger L. Bagula, Sep 29 2003

Keywords

• nonn

Crossrefs

Cf. A005185.

Programs

Mathematica

digits=750;
Hofstadter[n_Integer?Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n-1]] + Hofstadter[n - Hofstadter[n-2]];
Hofstadter[1] = Hofstadter[2] = 1;
a1=Table[Hofstadter[n], {n, 1, digits}];
f[x_, y_] := Abs[x-y]/; x-y<0;
f[x_, y_] := 0/; x-y>=0;
b=Table[If[f[a1[[n]], a1[[n-1]]]>0, a1[[n]], 0], {n, 2, digits}];
c=Delete[Union[b], 1]