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Sequence gives A087655(n) for those n such that A087655(n) = A087655(n+1).
0

%I #4 Mar 30 2012 17:34:13

%S 1,1,13,15,25,39,47,51,69,81,101,139,249,261,275,291,739,1243,2243

%N Sequence gives A087655(n) for those n such that A087655(n) = A087655(n+1).

%t Hofstadter123[n_Integer?Positive] := Hofstadter123[n] = Hofstadter123[Abs[n - Hofstadter123[n-1]]] + Hofstadter123[Abs[n - Hofstadter123[n-2]]]+ Hofstadter123[Abs[n - Hofstadter123[n-3]]] Hofstadter123[0] =Hofstadter123[1] = Hofstadter123[2]= Hofstadter123[3]= 1 digits=30000 ta=Table[Hofstadter123[n], {n, 1, digits}]; b=Table[If[ta[[n]]-ta[[n-1]]==0, ta[[n]], 0], {n, 2, digits}]; c=Delete[Union[b], 1]

%Y Cf. A087655.

%K nonn

%O 0,3

%A _Roger L. Bagula_, Oct 05 2003