login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A135156 a(n) = number of strings of length n that can be obtained by starting with abc and repeatedly doubling any substring of length >= 2 in place. 2
1, 0, 2, 0, 3, 1, 4, 0, 5, 2, 6, 1, 7, 3, 8, 9, 9, 7, 10, 34, 11, 36, 12, 136, 13, 190, 14, 567, 15, 1018, 16, 2445, 17, 5474, 18, 11371, 19, 28233, 20, 57961, 21, 143391, 22, 308793, 23, 740519, 24, 1668316 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A "weakly primitive" version of A135473. Cf. A135017.

Differs from A135017 in that the strings may contain repeated letters.

LINKS

Table of n, a(n) for n=0..47.

Index entries for doubling substrings

CROSSREFS

Sequence in context: A110514 A249122 A135157 * A328967 A277707 A316524

Adjacent sequences:  A135153 A135154 A135155 * A135157 A135158 A135159

KEYWORD

nonn

AUTHOR

David Applegate and N. J. A. Sloane, Feb 15 2008

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 April 1 18:50 EDT 2020. Contains 333168 sequences. (Running on oeis4.)