OFFSET
1,2
COMMENTS
a(n) is the number of bit strings of length n+3 with the pattern 01 at least twice, and without the pattern 110, see example. [John M. Campbell, Jan 25 2013].
FORMULA
a(n) = Fibonacci(n+6) - 4*n - 8. - Ralf Stephan, Feb 15 2004
EXAMPLE
From John M. Campbell_, Jan 25 2013: (Start)
There are a(3) = 14 bit strings of length 3+3 with the pattern 01 at least twice, and without the pattern 110:
000101, 001001, 001010, 001011, 010001, 010010, 010011,
010100, 010101, 010111, 100101, 101001, 101010, 101011
(End)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved