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 A006711 Describe previous term from the right (method A - initial term is 1). (Formerly M4778) 26
 1, 11, 21, 1112, 1231, 11131211, 2112111331, 112331122112, 12212221231221, 11221113121132112211, 212221121321121113312221, 113211233112211213111221321112 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Method A = 'frequency' followed by 'digit'-indication. REFERENCES J. H. Conway, personal communication. Akhlesh Lakhtakia and C. A. Pickover, Observations on the Gleichniszahlen-Reihe: An Unusual Number Theory Sequence, J. Rec. Math., Vol. 25 #3, pp. 189-192, 1993. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..24 Onno M. Cain, Sela T. Enin, Inventory Loops (i.e. Counting Sequences) have Pre-period 2 max S_1 + 60, arXiv:2004.00209 [math.NT], 2020. Trevor Scheopner, The Cyclic Nature (and Other Intriguing Properties) of Descriptive Numbers, Princeton Undergraduate Mathematics Journal, Issue 1, Article 4. Eric Weisstein's World of Mathematics, Look and Say Sequence Wikipedia, Look-and-say sequence FORMULA a(n+1) = A045918(A004086(a(n))). - Reinhard Zumkeller, Mar 02 2014 EXAMPLE E.g. the term after 1231 is obtained by saying "one 1, one 3, one 2, one 1", which gives 11131211. MATHEMATICA A006711[1]:=1; A006711[n_]:=A006711[n]=FromDigits[Flatten[{Length[#], First[#]}&/@Split[Reverse[IntegerDigits[A006711[n-1]]]]]]; Map[A006711, Range[15]] (* Peter J. C. Moses, Apr 22 2013 *) PROG (Haskell) a006711 n = a006711_list !! (n-1) a006711_list = iterate (a045918 . a004086) 1 -- Reinhard Zumkeller, Mar 02 2014 CROSSREFS Cf. A005150, A022506, A022482, A022507-A022513. Sequence in context: A163288 A092806 A138485 * A005151 A098155 A098154 Adjacent sequences:  A006708 A006709 A006710 * A006712 A006713 A006714 KEYWORD nonn,base,easy,nice AUTHOR STATUS approved

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Last modified November 28 09:12 EST 2020. Contains 338714 sequences. (Running on oeis4.)