A221369 - OEIS

A221369

A two-digit Look-and-Say sequence starting with 13: each term summarizes the increasing two-digit substrings of the previous term.

13, 113, 111113, 411113, 311113141, 311113114231141, 511113214123331141142, 511112113314121123131132233241142151, 711312313214115321122223124331232233241142251, 411412213214115221522423224125431432233241142143151153171

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

a(22) is the first term containing a zero; this is due to the fact that a(21) is the first term having exactly 10 occurrences of a two-digit number, namely 10 x 42.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..1000

Eric Weisstein's World of Mathematics, Look and Say Sequence

Wikipedia, Look-and-say sequence

Reinhard Zumkeller, Haskell program for two-digit Look-and-Say sequences

EXAMPLE

a(0) = 11: 1 x 13 --> a(1) = 113;

a(1) = 113: 1 x 11 and 1 x 13 --> a(2) = 111113;

a(2) = 111113: 4 x 11 and 1 x 13 --> a(3) = 411113;

a(3) = 411113: 3 x 11, 1 x 13 and 1 x 41 --> a(4) = 311113141.

PROG

(Haskell) -- See Link.