A171773 - OEIS

%I #12 May 03 2016 23:19:58

%S 1,111,311,13211,111312211,31131122211,1321132132211,

%T 111312211312111322211,3113112221131112311332211,

%U 13211321322113311213212322211,1113122113121113222123211211131211121332211,3113112221131112311332111213122112311311123112112322211

%N This sequence is a relative of the audioactive sequences. We generate it by starting with a symbol * and describe sequentially: *, 1*, 111*, 311*, 13211*,...

%C The interest of this is that if A_{n} is the n-th term of this sequence then A_{n} is a truncate of A_{n+3}. Thus the sequence gives rise to a triple A,B,C of infinite sequences of 1,2,3 such that B describes A, C describes B and A describes C.

%C This sequence serves as the initial portion of A001155, A001140, A001141, A001143, A001145, A001151, and A001154, as it is those sequences with the 'seed value' removed. - _James E Davis_, Apr 28 2016

%H Michael De Vlieger, <a href="/A171773/b171773.txt">Table of n, a(n) for n = 1..22</a>

%F Each term can be found by doing a look-and-say on the previous term and appending a 1. - _James E Davis_, Apr 28 2016

%e The term after 311 is one-three, two-one, one: i.e. 13211. - _James E Davis_, Apr 28 2016

%t NestList[FromDigits@ Append[Flatten@ Map[{Length@ #, First@ #} &, Split@ IntegerDigits@ #], 1] &, 1, 10] (* _Michael De Vlieger_, Apr 28 2016 *)

%Y Cf. A005150, A001155, A001140, A001141, A001143, A001145, A001151, and A001154

%K nonn,base

%O 1,2

%A Louis Hirsch Kauffman (kauffman(AT)uic.edu), Dec 18 2009

%E More terms from _James E Davis_, Apr 28 2016