%I #24 Aug 30 2022 02:08:51
%S 3,9,12,19,25,29,35,38,45,51,55,61,67,71,77,80,87,93,97,103,106,113,
%T 119,122,129,135,139,145,148,155,161,165,171,177,181,187,190,197,203,
%U 207,213,216,223,229,232,239,245,249,255,258,265,271,275,281,284,291,297,300,307,313,317,323,326,333,339,343,349,355
%N a(n) = floor(2*phi*floor(n*phi)) where phi = A001622.
%H Shiri Artstein-Avidan, Aviezri S. Fraenkel and Vera T. Sos, <a href="http://dx.doi.org/10.1016/j.disc.2007.08.070">A two-parameter family of an extension of Beatty sequences</a>, Discr. Math. 308 (2008), 4578-4588.
%H Shiri Artstein-Avidan, Aviezri S. Fraenkel and Vera T. Sos, <a href="http://www.wisdom.weizmann.ac.il/~fraenkel/Papers/coatp8.pdf">A two-parameter family of an extension of Beatty sequences</a>, preprint.
%p Digits := 200: a001622:= (1+sqrt(5))/2 : A140979 := proc(n) global a001622 ; floor(2*a001622*floor(n*a001622)) ; end: for n from 1 to 100 do printf("%d,",A140979(n)); end: # _R. J. Mathar_, Sep 05 2008
%t Table[Floor[2*GoldenRatio*Floor[n*GoldenRatio]],{n,70}] (* _Harvey P. Dale_, Feb 25 2018 *)
%o (Python)
%o from math import isqrt
%o def A140979(n): return (m:=n+isqrt(5*n**2)&-2)+isqrt(5*m**2)>>1 # _Chai Wah Wu_, Aug 29 2022
%Y Cf. A000201, A001622.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_, Sep 04 2008
%E Definition corrected and more terms from _R. J. Mathar_, Sep 05 2008