login
Number of (binary) bit strings of length n having an even length block of 0's followed by an odd length block of 1's.
0

%I #14 Mar 12 2024 08:48:15

%S 1,2,7,15,39,84,196,419,928,1965,4227,8871,18742,39032,81481,168606,

%T 349011,718371,1477783,3028412,6200296,12660171,25823604,52569417,

%U 106908199,217086287,440402878,892384788,1806730377,3654428154

%N Number of (binary) bit strings of length n having an even length block of 0's followed by an odd length block of 1's.

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,3,-5,-2).

%F G.f.: x^3/((1-2*x)*(1-3*x^2-x^3)).

%F a(n) = 2^n - A065455(n).

%Y Cf. A065455.

%K nonn,easy

%O 3,2

%A _Len Smiley_, Nov 26 2001