login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A205600 Start with first run [1,2] then, for n >= 2, the n-th run is a(n) times [a(1),...,a(n-1)]. 2
1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

What is the density of 1's in the sequence (it seems it is >0.7 see A206767 )? The length of the n-th run also appears to behave like c*n^2 with c=0.64...(see A205883).

LINKS

Table of n, a(n) for n=1..100.

EXAMPLE

First run is given by 12 so a(2)=2 and the second run is 2 times a(1)=1 and we get 1211. Next a(3)=1 hence the third run is 1 time [a(1),a(2)]=12 and we get 121112. a(4)=1 hence 4th run is 1 time 121 and we get 121112121 etc.

PROG

(PARI) /* compute 6555 terms: */

v=[1, 2]; for(n=2, 100, v=if(v[n]-2, concat(v, vector(n-1, i, v[i])), concat(concat(v, vector(n-1, i, v[i])), vector(n-1, i, v[i])))); a(n)=v[n]

CROSSREFS

Cf. A205883, A206767.

Sequence in context: A192393 A184303 A218545 * A133162 A276172 A322028

Adjacent sequences:  A205597 A205598 A205599 * A205601 A205602 A205603

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 10 2013

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 6 08:53 EST 2019. Contains 329788 sequences. (Running on oeis4.)