A001143 Describe the previous term! (method A - initial term is 6).

6, 16, 1116, 3116, 132116, 1113122116, 311311222116, 13211321322116, 1113122113121113222116, 31131122211311123113322116, 132113213221133112132123222116

Offset

1,1

Comments

Method A = 'frequency' followed by 'digit'-indication.

a(n+1) - a(n) is divisible by 10^5 for n > 5. - Altug Alkan, Dec 04 2015

References

S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 452-455.

I. Vardi, Computational Recreations in Mathematica. Addison-Wesley, Redwood City, CA, 1991, p. 4.

Links

T. D. Noe, Table of n, a(n) for n = 1..20

J. H. Conway, The weird and wonderful chemistry of audioactive decay, in T. M. Cover and Gopinath, eds., Open Problems in Communication and Computation, Springer, NY 1987, pp. 173-188.

S. R. Finch, Conway's Constant. [Broken link]

S. R. Finch, Conway's Constant. [From the Wayback Machine]

Example

The term after 3116 is obtained by saying "one 3, two 1's, one 6", which gives 132116.

Mathematica

RunLengthEncode[ x_List ] := (Through[ {First, Length}[ #1 ] ] &) /@ Split[ x ]; LookAndSay[ n_, d_:1 ] := NestList[ Flatten[ Reverse /@ RunLengthEncode[ # ] ] &, {d}, n - 1 ]; F[ n_ ] := LookAndSay[ n, 6 ][ [ n ] ]; Table[ FromDigits[ F[ n ] ], {n, 1, 11} ] (* Zerinvary Lajos, Mar 21 2007 *)

Crossrefs

Cf. A001155, A005150, A006751, A006715, A001140, A001141, A001145, A001151, A001154.

Sequence in context: A303213 A264511 A053334 * A177365 A138490 A022510

Adjacent sequences: A001140 A001141 A001142 * A001144 A001145 A001146

Keyword

nonn,base,easy,nice

Author

N. J. A. Sloane

Status

approved