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

1,2

Links

Table of n, a(n) for n=1..30.

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;

Prog

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

Crossrefs

Sequence in context: A026646 A026668 A111210 * A357212 A323583 A336724

Adjacent sequences: A033486 A033487 A033488 * A033490 A033491 A033492

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

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

Status

approved