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A036103 A look-and-say sequence: each term summarizes the previous two terms.

%I A036103 #17 Jul 14 2016 03:24:47
%S A036103 0,1,1110,4110,145120,1524124120,2534425120,354413624120,
%T A036103 16355433523120,26454463424120,36456453523120,46457443522120,
%U A036103 1736556443522120,2736556433623120,2756553463623120,2766552473622120
%N A036103 A look-and-say sequence: each term summarizes the previous two terms.
%C A036103 A look-and-say sequence. a(3) says 4 ones, 1 zero, which is the count of ones and zeros in the two previous terms. a(4) says 1 four, 5 ones, 2 zeros.
%C A036103 From the 28th term the sequence gets into a cycle of 117.
%H A036103 Reinhard Zumkeller, <a href="/A036103/b036103.txt">Table of n, a(n) for n = 0..611</a> = 5 periods
%H A036103 <a href="/index/Sa#swys">Index to sequences related to say what you see</a>
%e A036103 a(26) = 39283736554483723130;
%e A036103 a(27) = 39384726554493622120 = first term of first period;
%e A036103 a(28) = 39383736455493622120;
%e A036103 a(143) = 39283746553473823130 = last term of first period != a(26);
%e A036103 a(144) = 39384726554493622120 = first term of second period = a(27);
%e A036103 a(145) = 39383736455493622120 = a(28).
%t A036103 a[0] = 0; a[1] = 1; a[n_] := a[n] = Reverse /@ (Join[a[n-2] // IntegerDigits, a[n-1] // IntegerDigits] // Tally // SortBy[#, First]& // Reverse) // Flatten // FromDigits;
%t A036103 Array[a, 16, 0] (* _Jean-François Alcover_, Jul 13 2016 *)
%o A036103 (Haskell)
%o A036103 import Data.List (sort, group); import Data.Function (on)
%o A036103 a036103 n = a036103_list !! n
%o A036103 a036103_list = 0 : 1 : map (read . concatMap say . group . reverse . sort)
%o A036103                (zipWith ((++) `on` show) a036103_list $ tail a036103_list)
%o A036103                where say w = (show $ length w) ++ [head w]
%o A036103 -- _Reinhard Zumkeller_, Oct 05 2015
%Y A036103 Cf. A036059.
%Y A036103 Cf. A036106.
%K A036103 base,easy,nice,nonn
%O A036103 0,3
%A A036103 _Floor van Lamoen_