A001388 Describe the previous term (in base 3)!.

1, 11, 21, 1211, 111221, 1012211, 1110112221, 101102110211, 111021101221101221, 1011012211011222110112211, 1110211011222110211022110212221, 10110122110211022110122110222110121110211

Offset

1,2

Links

John Cerkan, Table of n, a(n) for n = 1..23

Greg Dresden and Jacob Siehler, Look, There's More to Say about Conway's Look and Say sequence, arXiv:2405.11103 [math.CO], 2024.

Example

To get the 6th term, for example, note that the 5th term has three (10 in ternary!) 1's, two (2) 2's and one (1) 1, giving 10 1 2 2 1 1.

Mathematica

a[1] := 1; a[n_] := a[n] = FromDigits[Flatten[{IntegerDigits[Length[#], 3], First[#]}& /@ Split[IntegerDigits[a[n-1]]]]]; Map[a, Range[25]] (* Peter J. C. Moses, Mar 24 2013 *)

Crossrefs

Cf. A005150.

Sequence in context: A007890 A063850 A005150 * A305660 A110393 A202627

Adjacent sequences: A001385 A001386 A001387 * A001389 A001390 A001391

Keyword

nonn,base,easy

Author

Thomas L. York

Status

approved