A033489 a(1) = 1, a(n) = 2*a(n-1) + a([n/2]).

1, 3, 7, 17, 37, 81, 169, 355, 727, 1491, 3019, 6119, 12319, 24807, 49783, 99921, 200197, 401121, 802969, 1607429, 3216349, 6435717, 12874453, 25755025, 51516169, 103044657, 206101633, 412228073, 824480953, 1649011689

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Programs

Maple

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;

PARI

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

Extensions

Better description and more terms from Benoit Cloitre, Jan 06 2004