OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
MAPLE
MATHEMATICA
a[n_]:= a[n]= If[n<3, 2^(n-1), 2*a[n-1] + a[Floor[n/2]]]; Table[a[n], {n, 40}] (* G. C. Greubel, Oct 14 2019 *)
PROG
(PARI) a=vector(99, i, i); for(n=3, #a, a[n]=2*a[n-1]+a[n\2]); a \\ Charles R Greathouse IV, Nov 29 2011
(Magma) a:= func< n | n lt 3 select 2^(n-1) else 2*Self(n-1) + Self(Floor(n/2)) >;
[a(n): n in [1..40]]; // G. C. Greubel, Oct 14 2019
(Sage)
@CachedFunction
def a(n):
if (n<3): return 2^(n-1)
else: return 2*a(n-1) +a(floor(n/2))
[a(n) for n in (1..40)] # G. C. Greubel, Oct 14 2019
(GAP)
a:= function(n)
if n<3 then return 2^(n-1);
else return 2*a(n-1) + a(Int(n/2));
fi;
end;
List([1..40], n-> a(n) ); # G. C. Greubel, Oct 14 2019
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Terms a(30) onward added by G. C. Greubel, Oct 14 2019
STATUS
approved