|
| |
|
|
A122536
|
|
Number of binary sequences of length n with no initial repeats.
|
|
4
| |
|
|
2, 2, 4, 6, 12, 20, 40, 74, 148, 286, 572, 1124, 2248, 4460, 8920, 17768, 35536, 70930, 141860, 283440, 566880, 1133200, 2266400, 4531686, 9063372, 18124522, 36249044, 72493652, 144987304, 289965744
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| An initial repeat of a string S is a number k>=1 such that S[i]=S[i+k] for i=0..k-1. In other words, the first k symbols are the same as the next k symbols, e.g. ABCDABCDZQQ has an initial repeat of size 4.
|
|
|
LINKS
| Guy P. Srinivasan, Java program for this sequence and A003000
|
|
|
EXAMPLE
| a(4)=6: 0100, 0110, 0111, 1000, 1001 and 1011.
|
|
|
CROSSREFS
| Cf. A003000.
Sequence in context: A030435 A063886 A003000 * A052953 A128209 A188538
Adjacent sequences: A122533 A122534 A122535 * A122537 A122538 A122539
|
|
|
KEYWORD
| more,nonn
|
|
|
AUTHOR
| Guy P. Srinivasan (srinivgp(AT)gmail.com), Sep 18 2006
|
| |
|
|
