A121175 - OEIS

A121175

Sequence S with the following properties: (i) a(1)=2; (ii) for n is S, a(n)=a(1)+a(2)+...+a(n-1); (iii) for n not in S, a(n)=the smallest number different from a(1), ..., a(n-1) not breaking property (ii).

%I #3 Apr 08 2015 08:54:17

%S 2,2,4,8,3,7,26,52,10,114,12,240,14,494,16,1004,18,2026,20,4072,22,

%T 8166,24,16356,27,32739,65478,29,130985,31,262001,33,524035,35,

%U 1048105,37,2096247,39,4192533,41,8385107,43,16770257,45,33540559

%N Sequence S with the following properties: (i) a(1)=2; (ii) for n is S, a(n)=a(1)+a(2)+...+a(n-1); (iii) for n not in S, a(n)=the smallest number different from a(1), ..., a(n-1) not breaking property (ii).

%C Taking a(1)=2 makes all terms distinct except for a(1)=a(2)=2

%Y Cf. A105753, A121053, A121174, A121173.

%K nonn

%O 1,1

%A Max Alekseyev, Aug 15 2006