A088205 Infinite audioactive word that shifts 1 place left under "Look and Say" method A, starting with a(0)=0.

0, 1, 0, 1, 1, 1, 0, 3, 1, 1, 0, 1, 3, 2, 1, 1, 0, 1, 1, 1, 3, 1, 2, 2, 1, 1, 0, 3, 1, 1, 3, 1, 1, 2, 2, 2, 1, 1, 0, 1, 3, 2, 1, 1, 3, 2, 1, 3, 2, 2, 1, 1, 0, 1, 1, 1, 3, 1, 2, 2, 1, 1, 3, 1, 2, 1, 1, 1, 3, 2, 2, 2, 1, 1, 0, 3, 1, 1, 3, 1, 1, 2, 2, 2, 1, 1, 3, 1, 1, 1, 2, 3, 1, 1, 3, 3, 2, 2, 1, 1, 0, 1, 3, 2, 1

Offset: 0

Author

Paul D. Hanna, Sep 22 2003

Keywords

• nonn

Comments

Positions of zero are given by A088206.

The sequence is obtained by starting with 0 and then successively appending the count (number of repetitions) and the value which is seen, term after term: "one zero, one one, one zero, three ones, one zero, ...". Otherwise said, the sequence is defined by "Start with 0 and append the result of "Look and Say" applied to the sequence". The "shifted left under Look and Say" property is thus an immediate consequence of the definition. A less trivial property is that there cannot be a number larger than 3 in this sequence. - M. F. Hasler, Jul 28 2015

Examples

			The initial terms {0,1,0,1,1,1,0,3,1,1,0,...} are shifted 1 place left by saying: "one 0, one 1, one 0, three 1's, one 0, ...", which drops the leading 0 to give {1,0,1,1,1,0,3,1,1,0,...}.
		

Crossrefs

Cf. A088206, A088203, A087282, A005150.

Programs

PARI

a=List(0);my(i=1);while(#a<200,listput(a,1);listput(a,a[i]);while(a[i++]==a[#a],a[#a-1]++));a \\ M. F. Hasler, Jul 28 2015