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

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.

Crossrefs

Cf. A005151, A047842.

Cf. A209234 (start=10), A209233 (start=11), A221368 (start=12), A221372 (start=19), A221373 (start=99).

Sequence in context: A048383 A230377 A254038 * A320213 A323037 A320617

Adjacent sequences: A221366 A221367 A221368 * A221370 A221371 A221372

Keyword

nonn,base

Author

Reinhard Zumkeller, Jan 13 2013

Status

approved