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A221369
A two-digit Look-and-Say sequence starting with 13: each term summarizes the increasing two-digit substrings of the previous term.
9
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
Eric Weisstein's World of Mathematics, Look and Say Sequence
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. A209234 (start=10), A209233 (start=11), A221368 (start=12), A221372 (start=19), A221373 (start=99).
Sequence in context: A048383 A230377 A254038 * A320213 A323037 A320617
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Jan 13 2013
STATUS
approved