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a(1)=1, a(n)=a(n-1)-1 if n is already in the sequence, a(n)=a(n-1)+5 otherwise.
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%I #9 Nov 21 2013 12:47:59

%S 1,6,11,16,21,20,25,30,35,40,39,44,49,54,59,58,63,68,73,72,71,76,81,

%T 86,85,90,95,100,105,104,109,114,119,124,123,128,133,138,137,136,141,

%U 146,151,150,155,160,165,170,169,174,179,184,189,188,193,198

%N a(1)=1, a(n)=a(n-1)-1 if n is already in the sequence, a(n)=a(n-1)+5 otherwise.

%F Conjectured to be asymptotic to 3n as n -> infinity.

%t lst={1};i=2;Do[If[MemberQ[lst,i],AppendTo[lst,Last[lst]-1], AppendTo[ lst,Last[lst]+5]];i++,{60}];lst (* _Harvey P. Dale_, Aug 20 2011 *)

%Y Cf. A079357, A079354, A080782, A064437.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Mar 07 2003