A316325 - OEIS

%I #9 May 07 2019 23:13:49

%S 1,3,6,10,12,15,17,20,24,26,29,32,34,37,41,43,46,50,52,55,58,60,63,67,

%T 69,72,74,77,81,83,86,89,91,94,98,100,103,105,108,112,114,117,120,122,

%U 125,129,131,134,138,140,143,146,148,151,155,157,160,162,165

%N Indices of 2's in A305389.

%H Robert Israel, <a href="/A316325/b316325.txt">Table of n, a(n) for n = 1..10000</a>

%p f:= 'f':

%p f(1):= 2: f(2):= 3: f(3):= (1,2,3):

%p S:= [1];

%p for i from 1 to 5 do T:= map(f,S); U:= map(f,T); S:= map(f,U); od:

%p select(t -> S[t+1]=2, [$0..nops(S)-1]); # _Robert Israel_, May 07 2019

%Y Cf. A305389.

%Y A316324, A316325, A316326 have the same relation to A305389 as A003144, A003145, A003146 do to the ternary tribonacci word A080843 (or A092782).

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Jul 09 2018