OFFSET
0,5
COMMENTS
A "run" is a contiguous block of consecutive identical terms.
FORMULA
a(n) = 2^n - 2*A000073(n+2).
a(n) = 2*A050231(n-1) for n>0.
G.f.: 2*x^4/((2*x-1)*(x^3+x^2+x-1)). - Alois P. Heinz, Dec 14 2015
EXAMPLE
For n=5 there are 6 such strings: 00000, 00001, 01111, and their complements.
PROG
(PARI) x='x+O('x^100); concat(vector(4), Vec(2*x^4/((2*x-1)*(x^3+x^2+x-1)))) \\ Altug Alkan, Dec 14 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Jeffrey Shallit, Dec 14 2015
EXTENSIONS
More terms from Alois P. Heinz, Dec 14 2015
STATUS
approved