The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A022506 Describe previous term from the right (method A - initial term is 0). 20
 0, 10, 1011, 211011, 21102112, 122112102112, 122112101112212211, 2122112231101112212211, 21221122311021132221221112, 12312211321321121021132221221112 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Method A = 'frequency' followed by 'digit'-indication. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..21 Eric Weisstein's World of Mathematics, Look and Say Sequence Wikipedia, Look-and-say sequence FORMULA For n > 1: a(n+1) = A045918(A004086(a(n))). - Reinhard Zumkeller, Mar 02 2014 EXAMPLE E.g. the term after 1011 is obtained by saying "two 1's, one 0, one 1", which gives 211011. MATHEMATICA a[0] = 0; a[n_] := a[n] = Split[IntegerDigits[a[n-1]]] /. L_List /; IntegerQ[L[[1]]] :> {Length[L], L[[1]]} // Reverse // Flatten // FromDigits; a /@ Range[0, 9] (* Jean-François Alcover, Nov 26 2019 *) PROG (Haskell) a022506 n = a022506_list !! n a022506_list = 0 : 10 : iterate (a045918 . a004086) 1011 -- Reinhard Zumkeller, Mar 02 2014 CROSSREFS Cf. A006711, A022482, A022507-A022513. Sequence in context: A037220 A179284 A138484 * A127117 A154703 A172163 Adjacent sequences:  A022503 A022504 A022505 * A022507 A022508 A022509 KEYWORD nonn,base,easy,nice AUTHOR EXTENSIONS More terms from Erich Friedman. STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 27 15:33 EST 2020. Contains 338683 sequences. (Running on oeis4.)