%I #14 Mar 08 2022 16:47:51
%S 1,1,3,11,42,165,654,2605,10398,41550,166116,664299,2656866,10626810,
%T 42505932,170021123,680079282,2720306730,10881206124,43524782946,
%U 174099048684,696396028620,2785583782248,11142334464693,44569336530174,178277343463830,713109368541588
%N A bisection of A002083.
%D H. Brocard, Query 4293, L'Intermédiaire des Mathématiciens, 23 (1916), 58-59. - _N. J. A. Sloane_, Mar 08 2022
%F a(0)=a(1)=1; a(2)=3; a(n) = 4*a(n-1) + ((-1)^(n-1)-3)/2 * a(floor((n-1)/2)). - _Carl R. White_, Oct 06 2017
%p A259858 := proc(n)
%p A002083(2*n+1) ;
%p end proc:
%p seq(A259858(n),n=0..30) ; # _R. J. Mathar_, Jul 09 2015
%t a[n_] := a[n] = If[n < 3, 1 + 2 Boole@ PrimeQ@ n, 4 a[n - 1] + ((-1)^(n - 1) - 3)/2*a[Floor[(n - 1)/2]]]; Array[a, 27, 0] (* _Michael De Vlieger_, Oct 06 2017 *)
%Y Cf. A002083, A245094.
%K nonn
%O 0,3
%A _N. J. A. Sloane_, Jul 07 2015