A221368 A two-digit Look-and-Say sequence starting with 12: each term summarizes the increasing two-digit substrings of the previous term.

12, 112, 111112, 411112, 311112141, 311112114121131141, 611212113214221231241, 211412113114421122123124131132141142161, 611412313414116621122123124331132341242144161, 411512213314216321122323224331132133234541142143144261162166

Offset

0,1

Comments

a(36) is the first term containing a zero; this is due to the fact that a(35) 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) = 12: 1 x 12 --> a(1) = 112;
a(1) = 112: 1 x 11 ana 1 x 12 --> a(2) = 111112;
a(2) = 111112: 4 x 11 and 1 x 12 --> a(4) = 411112;
a(3) = 411112: 3 x 11, 1 x 12 and 1 x 41 --> a(4) = 311112141.

Prog

(Haskell) -- See Link.

Crossrefs

Cf. A005151, A047842.

Cf. A209234 (start=10), A209233 (start=11), A221369 (start=13), A221372 (start=19), A221373 (start=99).

Sequence in context: A366716 A290742 A268767 * A083767 A285154 A153882

Adjacent sequences: A221365 A221366 A221367 * A221369 A221370 A221371

Keyword

nonn,base

Author

Reinhard Zumkeller, Jan 13 2013

Status

approved