|
Search: id:A065455
|
|
|
| A065455 |
|
Number of (binary) bit strings of length n in which no even block of 0's is followed by an odd block of 1's. |
|
+0
6
|
|
| 1, 2, 4, 7, 14, 25, 49, 89, 172, 316, 605, 1120, 2131, 3965, 7513, 14026, 26504, 49591, 93538, 175277, 330205, 619369, 1165892, 2188312, 4117045, 7730828, 14539447, 27309529, 51349169, 96468034, 181357036, 340753271, 640539142, 1203616849
(list; graph; listen)
|
|
|
OFFSET
|
0,2
|
|
|
FORMULA
|
G.f.: (1+x)^2/(1-3x^2-x^3)
|
|
EXAMPLE
|
a(5)=32-7=25 because 00111, 00101, 00100, 10010, 01001, 11001, 00001 are forbidden.
|
|
CROSSREFS
|
Cf. A061279 (forbids odd block 0's-odd block 1's), A065494, A065495, A065497.
Adjacent sequences: A065452 A065453 A065454 this_sequence A065456 A065457 A065458
Sequence in context: A054169 A065491 A072810 this_sequence A026010 A088813 A097596
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Len Smiley (smiley(AT)math.uaa.alaska.edu), Nov 24 2001
|
|
|
Search completed in 0.002 seconds
|
