A209233 A two-digit Look-and-Say sequence starting with 11: each term summarizes the increasing two-digit substrings of the previous term.

11, 111, 211, 111121, 311112121, 311212221131, 211212113221222231, 211312113421422123131132, 311212413114421122123331132134242, 411412313114421122123224331132233134141342144, 411312413414321322323124431232233234441242143244

Offset: 0

Author

Reinhard Zumkeller, Jan 13 2013

Keywords

• nonn
• base

Comments

a(16) is the first term containing a zero; this is due to the fact that a(15) is the first term having exactly 10 occurrences of a two-digit number, namely 10 x 31.

Examples

			a(0) = 11: 1 x 11 --> a(1) = 111;
a(1) = 111: 2 x 11 --> a(2) = 211;
a(2) = 211: 1 x 11 and 1 x 21 --> a(3) = 111121;
a(3) = 111121: 3 x 11, 1 x 12 and 1 x 21 --> a(4) = 311112121.
		

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

Crossrefs

Cf. A005151, A047842.

Cf. A209234 (start=10), A221368 (start=12), A221369 (start=13), A221372 (start=19), A221373 (start=99).

Programs

Haskell

-- See Link.