

A022506


Describe previous term from the right (method A  initial term is 0).


20




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, Lookandsay 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[n1]]] /. L_List /; IntegerQ[L[[1]]] :> {Length[L], L[[1]]} // Reverse // Flatten // FromDigits;
a /@ Range[0, 9] (* JeanFrançois 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, A022507A022513.
Sequence in context: A037220 A179284 A138484 * A127117 A154703 A172163
Adjacent sequences: A022503 A022504 A022505 * A022507 A022508 A022509


KEYWORD

nonn,base,easy,nice


AUTHOR

N. J. A. Sloane.


EXTENSIONS

More terms from Erich Friedman.


STATUS

approved



