A321509 a(1) = 1 and for any n > 1, a(n) = A321485(a(n-1)).

1, 11, 21, 121, 1121, 21121, 121121, 2121, 221, 2211, 2221, 3211, 13211, 113211, 2113211, 12113211, 112113211, 2112113211, 221113211, 223113211, 2213113211, 22113113211, 2221131211, 3221131211, 13221131211, 113221131211, 2113221131211, 12113221131211

Offset

1,2

Comments

This sequence is a variant of the Look and Say sequence A005150; here we use A321485 instead of A045918 to describe the previous term.

In contrast to A005150, this sequence is not monotonic.

The first digit 1 appear in a(1) = 1.

The first digit 2 appear in a(3) = 21.

The first digit 3 appear in a(12) = 3211.

The first digit 4 appear in a(288) = 2221134231131131211.

Will other digits also appear?

Is this sequence bounded?

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Rémy Sigrist, C++ program for A321509

Example

The first terms, alongside the corresponding blocks, are:
  n   a(n)        Blocks
  --  ----------  ------------------
   1           1                 (1)
   2          11               (1|1)
   3          21                (21)
   4         121               (121)
   5        1121           (1|1)(21)
   6       21121             (21121)
   7      121121           (121|121)
   8        2121             (21|21)
   9         221            (2|2)(1)
  10        2211          (2|2)(1|1)
  11        2221          (2|2|2)(1)
  12        3211              (3211)
  13       13211             (13211)
  14      113211         (1|1)(3211)
  15     2113211           (2113211)
  16    12113211          (12113211)
  17   112113211      (1|1)(2113211)
  18  2112113211     (211|211)(3211)
  19   221113211  (2|2)(1|1|1)(3211)
  20   223113211      (2|2)(3113211)

Prog

(C++) See Links section.

Crossrefs

Cf. A005150, A045918, A321485.

Sequence in context: A166707 A116525 A094623 * A034922 A015446 A254208

Adjacent sequences: A321506 A321507 A321508 * A321510 A321511 A321512

Keyword

nonn,base

Author

Rémy Sigrist, Nov 11 2018

Status

approved