

A205600


Start with first run [1,2] then, for n >= 2, the nth run is a(n) times [a(1),...,a(n1)].


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
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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 nth 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(n1, i, v[i])), concat(concat(v, vector(n1, i, v[i])), vector(n1, 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



