OFFSET
0,7
LINKS
Aashir Shukla et al., How many Binary Strings of length N contain within it the substring '11011'?, Mathematics Stack Exchange, circa Sep 09 2016.
FORMULA
G.f.: 1/(1-2*x) - (1+x^3+x^4)/(1-2*x+x^3-x^4-x^5) = x^5/((-1+2*x)*(x^5+x^4-x^3+2*x-1)).
Equals 2^n - A210021(n).
a(n) = Sum_{k>0} A277678(n,k). - Alois P. Heinz, Oct 26 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Oct 05 2016, following a suggestion from Rick L. Shepherd
STATUS
approved