A033489 - OEIS

%I #10 Mar 30 2012 18:38:42

%S 1,3,7,17,37,81,169,355,727,1491,3019,6119,12319,24807,49783,99921,

%T 200197,401121,802969,1607429,3216349,6435717,12874453,25755025,

%U 51516169,103044657,206101633,412228073,824480953,1649011689

%N a(1) = 1, a(n) = 2*a(n-1) + a([n/2]).

%p A033489 := proc(n) option remember; if n = 1 then 1 else A033489(n-1)+A033489(round(2*(n-1)/2))+A033489(round((n-1)/2)); fi; end;

%o (PARI) a(n)=if(n<2,1,(2*a(n-1)+a(floor(n/2))))

%K nonn

%O 1,2

%A _N. J. A. Sloane_.

%E Better description and more terms from _Benoit Cloitre_, Jan 06 2004