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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A157261 A run-length encoding of blocks of 2 in A090822. 1
1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 3, 1, 1, 1, 9, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 3, 1, 1, 1, 9, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 3, 1, 1, 1, 9, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 3, 1, 1, 1, 10, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 3, 1, 1, 1, 9, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 3, 1, 1, 1, 9, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

The assumption underlying this sequence is that the number 2 occurs isolated or in blocks of length 3 in A090822.

This sequence notes the size of successive blocks of length 3, that is, the number

of blocks of length 3 not interrupted by an isolated 2.

This is equivalent to counting the successive triples of indices of the form k, k+1, k+2 in A157041.

LINKS

Table of n, a(n) for n=1..108.

EXAMPLE

A090822(n)=2 at n=3 (isolated), n=6-7 (block), n=12 (isolated), n=15-17 (block),

n=19 (isolated), n=22 (isolated), n=25-27 (block), n=31 (isolated) n=34-36 (block),

n=38-40 (block), n=42-44 (block), n=47 (isolated). Determining the cluster size of

successive blocks, we write a(1)=1 (block at n>=6), a(2)=1 (block at n>=15), a(3)=1 (block at n=>25),

a(4)=3 (blocks at n>=34, n>=38, n>=42)), a(5)=1 (block at n>=53). a(16)=9 represents the 9 blocks

at n>=179, n>=183, n>=187, n>=192, n>=196, n>=200,... n>=213, followed by an isolated 2 at n=223.

CROSSREFS

Sequence in context: A195644 A143632 A130605 * A079110 A079619 A157603

Adjacent sequences:  A157258 A157259 A157260 * A157262 A157263 A157264

KEYWORD

nonn

AUTHOR

Paul Curtz, Feb 26 2009

EXTENSIONS

Edited by R. J. Mathar, Feb 27 2009

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 22 13:33 EDT 2017. Contains 286872 sequences.